Sera from 494 non-icteric patients admitted with illnesses other than overt hepatitis into the various hospitals in rural and urban Malaysia were tested for IgG antibody to hepatitis A virus. The overall antibody prevalence rate was 67.0% with rates increasing steadily from childhood 10 years old and under (39.4%) to middle-age and above (96.0%). No significant differences were noted between males (68.4%) and females (65.3%). The highest rate was in the Indians (80.6%), the lowest in the Chinese (55.9%) with Malays occupying intermediate position (70.3%). The rate in the rural patients (74.7%) was higher than that in the urban patients (65.5%) especially in the 21 to 40 year age-group where the rural patients had a rate of 96.7% compared with that in urban patients (61.1%). A comparison of antibody prevalence rates in different countries was made.