While more than 30 years have elapsed since the outbreak of Minamata disease in the area facing the Shiranui Sea, Kyushu, Japan, little is yet known regarding the health conditions of Minamata disease patients. Patients were surveyed for ADL and subjective complaints to evaluate their current life (1, 227 cases). Controls, aged 40 or over, were selected from residents of a rural town, not polluted by methylmercury and near the patients' residence (3, 212 persons). The results are as follows: 1) ADL of patients under 30 years old (prenatal exposure) called fetal Minamata disease was poorer than those aged 30 or over (postnatal exposure) and the distribution of subjective complaints differed between the two groups. 2) The subjective complaints of the patients aged 40 or over were classified into two categories: those where frequency increased with age, and those, although high, remained unchanged with age (constant group). Among controls, the frequency of the subjective complaints increased with age. 3) In patients aged 40 or over, subjective complaints relating to sensory disturbance were included in the constant group. These results suggest that the late effects of methylmercury exposure differs with age at which exposure to methylmercury occurred, and that there are differences in the health effects associated with aging between the patients and the control population.