A predominance of small, dense, low-density lipoprotein particles (pattern B) has been associated with increased cardiovascular risk independent of absolute cholesterol levels in primarily white populations. Because of the putative association of pattern B with increased risk, some investigators have proposed that routine measurement of low-density lipoprotein particle size may be beneficial for cardiovascular risk assessment. Because no studies have specifically examined this possibility in African-Americans, it remains unclear whether measurement of low-density lipoprotein particle size adds information beyond that of traditional lipid risk factors. We compared standard lipid profile measurements with extended measurements concurrently in an apparently healthy, high-risk population of African-American siblings of patients who had premature cardiovascular disease. We determined the extent to which patients who had pattern B would be identifiable from the usual lipid profile. A high triglyceride level alone was a strong independent correlate of pattern B. In subjects whose triglyceride level was >/=150 mg/dl, 67% had pattern B, whereas only 17% of subjects whose triglyceride level was <150 mg/dl had pattern B. The area under the receiver-operating characteristic curve was 0.77. Our data suggest that the standard lipid profile, primarily fasting triglyceride measurement, appears to be a useful surrogate for direct measurement of particle size in a high-risk African-American population.