An earthquake struck Haiti on 12 January 2010. More than 200,000 people were killed and more than 300,000 people were injured in this earthquake. The Japanese government dispatched the Japan Disaster Relief Medical Team (JDR-MT) to Haiti on 16 January. This is the report of the medical activities of JDR-MT in Haiti. The JDR-MT consisted of 27 members, including four medical doctors, seven nurses, one pharmacist, one radiologist, one medical technologist, two emergency medical technicians, and 11 logisticians. The JDR-MT was equipped with medicines for 1,000 patients, a portable x-ray system, and ultrasound diagnostic equipment. The JDR-MT performed relief activities at Leogane City, which was 40km west of the capital of Port-au-Prince, and was the first medical team that entered the Leogane area after the earthquake. The JDR-MT treated 534 patients for eight days. The male-female ratio of total patients was 180/354, and the male-female ratio of 242 injured cases treated by the JDR-MT was 80/162. Among the patients treated by the JDR-MT, 100 were diagnosed as bone fractures with the portable x-ray system. There were 17 cases of open bone fractures and 15 cases of pelvic fractures. The male-female ratios were 28/72, 4/13, and 1/14 respectively. The total number of female patients was approximately double compared with the number of male patients in this experience. The proportion of female patients was much higher in the cases of severe injury, such as open bone fractures and pelvic fractures.