The aim of the study was to examine whether school performance was reduced in children with very-low birthweight beyond what could be explained by the deficit in intelligence-score at 4 years of age. Participants (n=333) examined at 4 years of age included three subgroups on the basis of birthweight: very-low birthweight (VLBW < 1501 g; n=102), low birthweight (LBW 1500-2300 g; n=139), and normal birthweight (NBW > or = 2500 g; n=92). The general cognitive index index (CGI) from the McCarthy Scales of Children's Abilities was used as an intelligence measurement at this assessment. At 18 to 20 years of age a telephone interview concerning school performance was conducted. Two hundred and fifty-seven participants (53% male, 47% female) entered the analysis. A model with School Performance score after the last year of compulsory school as the outcome variable, and McCarthy GCI and birthweight group as predicting variables, was used in linear regression analyses. Twenty-four per cent of the variance was explained. Birthweight had no influence in this model. In conclusion, the study did not find that birthweight influenced school performance beyond that represented by the McCarthy GCI found at age 4 years.