Infant mortality data had been collected through a National Household Health Survey in 7 provinces, which was conducted in August 1985 through May 1986. Retrospectively, the sampled population were interviewed about the occurence of births and deaths in the last one year period. Diagnosis for causes of deaths were made by medical doctors, based on verbal "autopsy". In the survey, 7951 live births and 571 infant deaths were recorded, and the infant mortality rate was 71.8 per 1000 live births. Comparing to 1980 Health Survey, the infant mortality rate was 99.7 per 1000 live births. Immunizable diseases were the underlying cause of 1926.0 infant deaths per 100,000 live births, i.e. covering 28.0% infant deaths. Within this group, tetanus was the most prevalent, it killed 1383.5 infants per 100,000 live births, i.e. 19.4% infant deaths. Diarrheal diseases were the underlying cause of 1119.8 infant deaths per 100,000 live births, i.e. 15.5% infant deaths. While diarrhea associated infant deaths were found in 18.7% cases. Respiratory infections, as an underlying cause, killed 867.8 infants per 100,000 live births, i.e. 12.1% infant deaths. Respiratory infection associated deaths were found in 1798.5. infants per 100,000 live births. Perinatal disorders frequently occurred during the neonatal periode (less than 1 month), and it killed 1433.8 infants per 100 000 live births.