If you would like to volunteer your medical services in Kiribati, then Tarawa hospital in the capital is a good. Voice. There is also a medical facility in Kiritimati.  Most people travel to tarawa for medical treatment.

Best contact details are listed below:

Ministry of Health and Medical Services

P.O. Box 268, Bikenibue (Nawerewere), Tawara, Kiribati
Tel:(686) 28100
WHO Country Liaison Officer in Kiribati
World Health Organization
Nawerewere, Tarawa, Kiribati
P. O. Box 210,
Bikenibeu, Tarawa,
Tel:(686) 28231