The short answer
Uninsured motorist coverage pays your injury costs when an at-fault driver has no insurance. See why it matters for motorcyclists and where it is required.
Uninsured/underinsured motorist coverage pays for a rider's own injuries — and in some forms, the bike — when an at-fault driver has no insurance or too little to cover the harm they caused. It exists for the crash that liability coverage cannot help with: the one where the rider did nothing wrong and the other driver cannot pay. It is mandatory in some states and optional in others. For a motorcyclist, given how exposed a rider is and how many drivers carry nothing, it is one of the highest-value coverages on the policy.
Direct answer: what uninsured motorist coverage does
Uninsured motorist (UM) coverage pays the rider's own injury costs when an at-fault driver has no insurance. Underinsured motorist (UIM) coverage does the same when the at-fault driver has insurance, but not enough to cover the rider's injuries. The two are usually sold together as UM/UIM coverage [Insurance Information Institute, 2024].
This fills a specific and dangerous gap. Liability coverage pays the other party when the rider is at fault — it does nothing for the rider, and it does nothing when someone else is at fault and uninsured. In that crash, the rider is hurt, blameless, and facing an at-fault driver with no policy to collect from. Without UM/UIM, the rider's options shrink to their own health insurance, their own savings, or suing a driver who had no money for insurance and likely has none for a judgment. UM/UIM is the coverage that steps in and pays. Some states also offer uninsured-motorist property-damage coverage for the bike itself; the bodily-injury side is the core.
What this coverage does
UM/UIM bodily-injury coverage pays for the rider's medical bills, lost income, and related injury costs after a crash caused by an uninsured or underinsured driver, up to the UM/UIM limit on the policy. Underinsured coverage works as a top-up: if the at-fault driver carries a small minimum-limit policy that runs out before the rider's injuries are paid, UIM covers the shortfall up to the rider's own limit.
Two details shape the coverage. The first is the limit — UM/UIM is worth carrying at a limit that reflects what a serious motorcycle injury actually costs, not a token minimum, because a motorcyclist in a crash with a car tends to be the one badly hurt. The second is how the coverage interacts with medical payments and health insurance: UM/UIM, med-pay, and health coverage can each contribute after a crash, and the rules for coordinating them vary by state. A rider should not assume health insurance makes UM/UIM redundant — health insurance does not replace lost income, and UM/UIM is built for exactly the costs a motorcycle injury runs up.
Who needs it
Almost every motorcyclist benefits from UM/UIM, and the reason is structural. A meaningful share of drivers on the road carry no insurance at all, and many more carry only a state-minimum policy too thin to cover a serious injury [Insurance Information Institute, 2024]. A motorcyclist hit by one of those drivers is both more likely to be seriously hurt and less likely to be paid — the worst combination. UM/UIM is the coverage that addresses it directly.
The need is sharpest for a rider in a state with a high uninsured-driver rate, a rider who commutes in heavy traffic, and any rider on liability-only — because a liability-only rider with no UM/UIM has, in an at-fault-by-someone-else crash, no coverage of their own at all. The case is weaker only where a rider's state already mandates UM/UIM at a solid limit (in which case the rider has it by default) or where the rider has chosen very high limits and accepts the exposure. For most riders, UM/UIM is inexpensive relative to what it protects, and skipping it is a poor trade. The liability-only page explains the gap UM/UIM closes.
What it costs
UM/UIM is one of the better-value coverages on a motorcycle policy: the premium it adds is modest relative to the protection, because the coverage pays out only in the specific scenario of an uninsured or underinsured at-fault driver. As a methodology-attributed frame — not a quote — adding UM/UIM commonly costs a modest share of the liability premium, and raising the UM/UIM limit costs more but stays inexpensive against the size of a serious injury claim.
In states that mandate UM/UIM, the cost is already built into the required policy. In states where it is optional, a rider is choosing whether to add it — and the modest premium is usually worth it. The cost lever the rider controls is the limit: a higher UM/UIM limit costs more and is the version that actually protects against a severe injury. The usual discounts — a safety-course discount, multi-bike and bundling discounts, paying in full — apply to the overall premium. For how the full number is built, see how much motorcycle insurance costs. Ask the carrier what UM/UIM adds and at what limit, and check the requirements guide for whether the rider's state mandates it.
Which providers offer it
UM/UIM coverage is available on motorcycle policies from every major insurer; in states that mandate it, the carrier includes it by default.
State Farm carries uninsured/underinsured motorist coverage as standard on its motorcycle policy [Insurance Information Institute, 2024]. Progressive, GEICO, Allstate, Nationwide, Harley-Davidson Insurance, and the other major carriers offer UM/UIM as a coverage on the motorcycle policy — included where the state requires it, elective where it does not. Because state law drives whether UM/UIM is mandatory and at what minimum, a rider should ask the carrier the specific question: is UM/UIM included or optional in my state, and what limit is available. A rider in a state where it is optional should treat adding it as the default choice given the value. Compare carriers in the provider reviews and confirm the UM/UIM terms for your state.