Background: ALDH1A1 and ALDH3A1 were reported to be highly expressed in some cancerous tissues. The aim of this study was to assess ALDH1A1 and ALDH3A1 expression and cellular localization in a spectrum of melanocytic lesions, ranging from common melanocytic nevi (CMN) and dysplastic nevi (DN) to acral melanoma (AM). We also compared the clinicopathological correlation of AM in a large Chinese population. Material and Methods: We used purified class-specific antibodies against ALDH1A1 and ALDH3A1 to elucidate the cellular distribution of these proteins in a human tissue microarray derived from 20 patients with CMN, 12 patients with DN, and 80 patients with primary acral MM. The cytoplasmic immunostaining score was obtained by multiplying the percentage of antigen-positive cells by their average immunostaining intensity. Mean 士 S.E.M. for each experimental group was calculated and compared. The relationships between AJCC TNM stage and cytoplasmic scores of ALDH1A1 and ALDH3A1 were examined. Results: A statistically higher score for ALDH1A1 staining was noted in CMN than in DN (p < 0.028). ALDH3A1 staining was significantly different between CMN and AM. No statistical differences in survival and no association between cytoplasmic staining of both enzymes and other clinical parameters were demonstrated. Conclusion: ALDH1A1 and ALDH3A1 were differentially expressed in CMN, DN, and AM; yet, these enzymes may not be appropriate for use as prognostic factors.