This article investigates the quality of age reporting in the 1985 Indonesian intercensal population survey (SUPAS 85). It provides the only evidence on national fertility and mortality trends between the 1980 and 1990 censuses. The age and sex data are compared to the 1971 and 1980 census results to determine if SUPAS 85 represents an improvement or a deterioration in data quality and to analyze error consistency. The data show some improvement in age heaping, which has been unusually high in Indonesia, but the improvement was confined to Java, Bali, West Nusa Tenggara, and parts of Sumatra. Even in most of these cases, SUPAS 85 merely maintained approximately the same level of reporting accuracy achieved in the 1980 census. None of the provincial age-sex distributions is accurate according to UN criteria. In the outlying provinces, SUPAS 85 was worse than the last census. The patterns of the age discrepancies are very different in SUPAS 85 compared to the 1980 census. SUPAS 85 showed more than the expected number of females in their late 20s and fewer than expected in their early 30s. Among children, males aged 5-9 appear to have been overenumerated; so were girls the same age, but not to the same extent. Whether through census survival rates, age or sex ratios, or smoothing procedures, anyone interested in Indonesian demographic trends needs to be aware of errors in age statements and their pattern by age and sex.