Travel insurance for Ajaccio and Corsica is worth arranging before you travel, and the picture is similar to mainland France with one island twist. Corsica is part of France and runs on the French public health system, so a European health card is genuinely useful here, but the island's location means a serious case can involve transfer to the mainland, and the card has limits that make travel insurance worth carrying.
Your health card works in Corsica
Corsica is French territory, so an EHIC or a UK GHIC is valid here, letting you access necessary and urgent state healthcare on the same basis as a French resident. Healthcare in Corsica is of a good standard, with hospitals in the larger towns including Ajaccio. The card covers necessary and unplanned care, including for chronic conditions, which makes it a real benefit for routine problems.
Why insurance still matters
The card never covers everything. It does not cover private treatment or planned care, and, importantly, it does not cover rescue or repatriation home. If you had a serious accident or illness in Corsica and needed a medically escorted flight back to your home country, that cost falls to you unless a travel policy covers it, and it can run to tens of thousands. Because Corsica is an island, a complex case may also mean transfer to a larger hospital on the French mainland, which insurance can help arrange and pay for. For visitors from outside Europe, the card does not apply at all, so insurance is the primary protection.
Choosing a policy
Carry both if you have them: the EHIC or GHIC for state care, and a travel policy for repatriation, private treatment, belongings, and cancellation. If you plan hiking on the GR20 or watersports, confirm those activities are covered, since some are excluded. Subscription-style cover such as SafetyWing suits long or multi-country trips, while a fixed per-trip policy is usually better value for a single visit. Buy the cover before you leave home, because most insurers will not sell or honour a policy once your trip has already started.