The Dubowitz gestational age was compared to the obstetric clinical age of 119 predominantly black mother-infant pairs for whom certain clinical criteria were met. Forty-five hypertensive and 74 nonhypertensive gestations with infant birth weight less than 2500 g were evaluated. Overall the clinical age was 33.6 +/- 4.5 weeks versus 34.7 +/- 4.3 weeks by Dubowitz age (P = NS). The Dubowitz age differed from clinical age by more than 2 weeks in 33.6% (40/119). Of gestations under 33 weeks (clinical age) (N = 45) the clinical age was 30.1 +/- 2.4 weeks as compared to the Dubowitz age of 32.2 +/- 2.7 weeks (P less than .01). Fifty-one percent (23/45) of Dubowitz ages were more than two weeks discordant with the clinical age. The Dubowitz assessment of gestational age may be unacceptably inaccurate in the determination of gestational age in low birth weight infants, particularly in those whose gestational age is less than 33 weeks. The findings suggest that studies in which conclusions were based on the Dubowitz age assessment may need reevaluation.