Background: Elastin peptides stimulate the development of mouse melanocytes in neural crest culture. Ferrous ferric chloride (FFC) promotes mammalian melanocyte growth in culture. However, it is unclear whether elastin peptides in the presence of FFC can stimulate human melanocyte growth in situ. Objectives: This study aimed to investigate the mechanism of human melanocyte growth for skin and stem cell science since melanocytes control human skin color. Methods: In this clinical trial study, a lotion containing elastin peptides and/or FFC was applied to the normal skin of 6 volunteers twice a day for 1 to 3 months. Punch biopsies were taken from treated skin and surveyed by histochemical methods using the dopa reaction (detect melanocytes) and dopa-premelanin reaction (detect melanocytes and melanoblasts). Elastin fibers were detected by Victoria blue staining. Results: Only the combined treatment of elastin peptides and FFC increased melanocyte populations in addition to dopa reactivity, melanogenesis, dendritogenesis, and epidermal melanin pigmentation. Mitotic divisions of melanocytes were also observed. However, the melanoblast population failed to increase, and no mitotic melanoblasts were observed. In the dermis, elastin fibers became thicker and denser after the treatment. The data of statistical analyses were performed by tabulation, mean, and SD on Microsoft Excel for Macintosh OS Catalina 10 system. Conclusions: Our present study suggests that elastin peptides with FFC can promote melanocyte growth, melanin synthesis, skin pigmentation, and elastin fiber formation. Our study can be expected to contribute to advancing skin and stem cell science.