Foamy virus evolution closely parallels that of the host species, indicating virus-host coadaptation. We studied simian foamy viruses (SFVs) from common marmosets, spider monkeys, and squirrel monkeys, New World monkey (NWM) species that share geographic ranges. The TRIM5alpha protein from each of these NWM species inhibited the replication of at least one of the SFVs associated with the other two species but did not affect the replication of its own SFV. Thus, TRIM5alpha has potentially shaped the evolution of SFVs in NWM hosts. Conversely, SFVs may have influenced the evolution of TRIM5 variants in New World primates.