Fourteen long-term human malignant melanoma cell lines established from biopsy specimens, malignant effusions and the peripheral blood are reported. Methods of culture, heterologous transplantation studies and characterization of these cell lines are presented. Several of these cell lines have retained the ability to produce pigment over a period of years, permitting bioassays at a subcellular level. Studies of cell lines grown with and without tyrosine and some of the theoretical uses of human melanoma cell lines are presented.