The association between microalbuminuria and blood pressure levels was examined in young white and black adults (n = 1131) aged 19 to 32 years. Urinary ratio of albumin (mg/L) to creatinine (mmol/L) was used as an estimation of urinary albumin excretion. Black men and women compared with their white counterparts had higher levels of blood pressure. Significantly positive correlations between urinary albumin excretion and systolic and diastolic blood pressures were observed in black men (r = 0.20 and r = 0.24, P < .01) and black women (r = 0.15 and r = 0.14, P < .05). Similar correlations of significance were not seen in the white counterparts. Systolic and diastolic blood pressure levels were significantly higher in normotensive black subjects (< 140/90 mm Hg) with increased urinary albumin excretion (> or = 90th percentile) than in those without increased urinary albumin excretion. After accounting for potential confounding by age, sex, and body mass index, blacks in the uppermost systolic and diastolic blood pressure group were 7.1 times (95% CI, 2.0 to 25.8) and 4.8 times (1.3 to 18.3), respectively, as likely to have elevated albumin/creatinine excretion as those in the lowest group. In contrast, the likelihood for elevated albumin/creatinine excretion were 0.9 times (95% CI, 0.5 to 2.2) and 1.1 times (0.5 to 2.3), respectively, in whites, which were not significant. These data suggest that a stronger association between blood pressure levels and urinary albumin excretion exists in young blacks than in whites, which supports the notion that blacks may be more susceptible to renal damage from relatively low levels of blood pressure increases.(ABSTRACT TRUNCATED AT 250 WORDS)