The effect of factors surrounding the intranatal and early postnatal period on mental development of very low birthweight infants was evaluated statistically. The subjects in this study were very low birthweight infants born at under 1,500g having been treated at the Nagoya Daini Red Cross Hospital, amounting to 161 subjects. The subjects were evaluated by the Tsumori-lnage test for infant mental development at half-year intervals. Covariance structure analysis of the correlation between intranatal and early postnatal factors and mental development of the very low birthweight infants at ages 1 and 2 revealed direct influence of: 1) birth weight and gestational age in weeks on mental development at age 1, and 2) ophthalmological aberrations and respiratory disorder on mental development at age 2. © 1998 OPA (Overseas Publishers Association).