Clinical studies suggest that African-American (AA) prostate cancer patients manifest a more aggressive form of the disease compared with white prostate cancer patients. However, the biological underpinnings of this potential difference remain unresolved. To address this issue, we used specific quantitative immunostaining protocols to determine whether a panel of biomarkers related to apoptosis including caveolin-1, bcl-2, p53, and c-myc were differentially expressed in AA versus white prostate cancer patients with similar clinical and pathological characteristics. We further attempted to correlate biomarker positivity with proliferation-related markers including Ki-67 labeling index and apoptotic index. Interestingly, our results indicated that only the incidence of caveolin-1 staining was significantly different between these two ethnic/racial groups of prostate cancer patients. The incidence of caveolin-1 staining in white patients was 17% compared with 39% in AA patients (P = 0.0048; Fisher's exact test). In addition, the percentage of caveolin-1-positive prostate cancer cells was also higher in moderately differentiated (Gleason score 6) prostate cancer patients in AA versus whites. Because caveolin-1 has been shown previously to demonstrate antiapoptotic activities in prostate cancer cells, our results suggest that differences in caveolin-1 expression may in part underlie the apparent differences in the clinical virulence of this disease in AA versus white prostate cancer patients.