The local police headquarters for the island is in Ban Dan Mai, on the east coast. There is also a small police office at the northern end of White Sands Beach. The island does not have tourist police. Should you need to call them, their number is (039) 521 657.
There is a small hospital in Ko Chang (tel: 039 521 657) just south of where the mainland ferry arrives. There are also medical centres at White Sands Beach (tel: 01 865 8358), Khlong Son, Kai Bae and Khlong Prao. There is also a clinic in Ko Maak and a private hospital off the island in Trat for major accidents and emergencies.
The immigration office is in Laem Ngop, who deal with visa extensions. If you have a 30-day visa, you can extend this for up to 10 days (tel: 039 597 261), but if you are looking for a much more lengthy stay, then go into Cambodia (see our section on Visa extensions).