A new human endogenous retroviral family (HERV-F) has recently been identified from human chromosome 7q31.1-q31.3 that was identical to the XA34 cDNA clone isolated from a human glioma cDNA library with an ERV-9 env probe. We investigated pol fragments of the HERV-F family from the Old World monkeys (crab-eating monkey, African green monkey, and baboon) and analyzed these with the HERV-F (Hu-XA34). Fifteen pol fragments of the HERV-F family were detected from the Old World monkeys. They showed a high degree of sequence similarity (81-99%) with that of the HERV-F (Hu-XA34). Phylogenetic analysis of pol fragments with those of the human genome distinctively showed five groups, indicating that HERV-F family could be amplified at least five times after the original integration into the monkey genome or represent integration events independently during primate evolution.