Aldehyde dehydrogenase 1 (ALDH1) has been proposed as biomarker of stem cells for certain human cancers. ALDH1 expression has been correlated with poor patient outcomes in a variety of malignancies but better patient outcomes in others, and its prognostic significance in malignant melanoma is unclear. Thus, 68 melanoma patients with comprehensive clinical and pathologic follow-up data were used to construct a tissue microarray. A modified histological score (H-score) with a maximum score of 300 was used to quantify immunohistochemical staining for ALDH1. Survival time was defined as the time between diagnosis and melanoma-specific death. Using univariate logistic regression, a low (<80 H-score) ALDH1 score showed 3.7-fold increase in risk for melanoma-specific death within 10 years when compared with high (>80) ALDH1 levels (P=0.017). Odds of MSD were lower by a factor of ~0.9 for each 10-point increase in H-Score. Median survival time was 44.1 months and 180.9 months for patients with low and high ALDH1 expression, respectively. Using multivariate analysis, ALDH1 H-score was found to be an independent prognostic factor. These findings suggest that ALDH1 expression in malignant melanoma has a favorable effect on patient survival. Further study is needed elucidate the function of this enzymatic protein in melanoma progression.