Retroviral genetic rearrangements can result from reverse transcriptase template switching. Most published data suggest that errors such as base misincorporation occur at similar frequencies for HIV-1 and for simple retroviruses such as spleen necrosis virus (SNV) and murine leukemia virus (MuLV). However, previous reports have suggested that template switch-mediated recombination is much more frequent for HIV-1 than for simple retroviruses. In this report, direct repeat deletion vectors similar to those previously used for measuring template switching events for SNV and MuLV were developed for HIV-1. Forward mutation rates and the frequency of template switching during a single cycle of HIV-1 replication were determined. The frequency of HIV-1-mediated repeat deletion was measured for three separate internal repeats in lacZ and was compared to rates observed with identical repeats for MuLV. The results indicated that the error rate and the frequency of repeat deletion of HIV-1 were similar to those of MuLV.