By using tissue microdissection and polymerase chain reaction (PCR) techniques, we examined 85 prostate tumors that were paired with normal tissues from the same patients for allelic loss at 26 highly polymorphic microsatellite sequences, 21 spanning 8p and 5 localized to 8q. Sixty‐four tumors (75%) demonstrated loss of at least one 8p locus. Separate distal and proximal regions of deletion were observed as well as an intervening, staggered breakpoint. A novel region of homozygous deletion of sequences at the D8S87 locus was detected both by multiplex PCR and by fluorescence in situ hybridization within this breakpoint region. These data suggest that a tumor‐suppressor gene mapping to proximal 8p is deleted frequently and is likely to be important for tumorigenesis in prostate tumors. Genes Chromosomes Cancer 23:255–262,1998. © 1998 Wiley‐Liss, Inc.