To assess the efficacy of early intervention (EI) for very-low-birth-weight (VLBW) infants, we evaluated 62 2 year old children who were enrolled in an EI program and 48 control subjects aged 2 years. We determined the subjects' developmental quotients (DQ) and obtained information about the parents' evaluation of the children from a questionnaire sent to the parents. There was no significant difference in the DQ between the EI group and the control group. However, based on the responses to the questionnaire, subjects in the EI group showed slight, but statistically marginally significant, improvements in behavioral problems, especially a decrease in hyperkinesia, in adjusting to a circadian sleep cycle, and an improvement in language development, as compared with the control group (P < 0.1). Thus, EI for VLBW infants is considered useful to enhance some areas of development.