We have utilized a combination of conventional and spectral karyotyping (SKY) techniques and allelotype analysis to assess numerical and structural chromosome alterations in two cell lines derived from normal human prostatic epithelium, and three cell lines derived from human prostate primary tumor epithelium, immortalized with the E6 and E7 transforming genes of human papilloma virus (HPV) 16 or the large T-antigen gene of simian virus 40 (SV40). These studies revealed trisomy for chromosome 20 and rearrangements involving chromosomes 3, 4, 8, 9, 10, 16, 17, 18, 19, 21, or 22. In addition, the four HPV-immortalized cell lines exhibited extensive duplications or translocations involving the 11q chromosomal region. Interestingly, allelotyping data disclosed loss of 8p sequences in two of the three primary tumor-derived cell lines, and SKY data revealed that the loss of 8p sequences was directly due to i(8q) chromosome formation and/or other structural alterations of chromosome 8. This provides intriguing evidence that 8p loss in primary human prostate tumors may, in some cases, result from complex structural rearrangements involving chromosome 8. Moreover, the data reported here provide direct evidence that such complex structural rearrangements sometimes include i(8q) chromosome formation.