We report here the establishment and characterization of a corpus cavernosum cell line (DS-1) from human penile tissue. This is the first cell line of its type derived from cavernosum tissue. DS-1 cells have become immortalized in culture, and show growth in monolayers. These cells have a doubling time of about 45 h in in vitro culture. Cytogenetic analysis by G-banding demonstrated a diploid karyotype with a model chromosome number of 46. The chromosome constitution of DS-1 cells was found to be male (XY), in 28/30 cells scored. Two of the 30 cells showed an extra structurally rearranged "marker" chromosome, that appeared to be a derivative of chromosome 18 with excessive chromosome on the short arm. Ploidy analysis revealed that the majority of DS-1 cells had a DNA index of one. About 35% cells were found to be in G-1 phase and 52% cells in S phase. Light and electron microscopy of DS-1 cells and original penile tissue showed typical characteristics of this tissue. Immunocytochemistry studies using antibodies to smooth muscle actin, desmin, vimentin and cytokeratin (LP34, CAM5.2) showed that the DS-1 cell line had predominantly smooth muscle cells, as these cells were positive for smooth muscle actin, desmin and vimentin.