In the fall of 1987 an attempt to establish a Herpesvirus simiae (B-virus)-negative rhesus monkey (Macaca mulatta) breeding colony was initiated at the Armstrong Laboratory. A serologic testing program was used to identify all monkeys into groups that were either positive or negative to B-virus based on serologic tests. Segregation of the groups allowed the creation of breeding harems that were exclusively seropositive or -negative to B-virus. Animals that were serologically positive were kept in breeding to maintain infant production levels not unlike those previous to segregation. Decreasing numbers of animals converted to a positive status during the first three serum tests for B-virus in the program. During 1990, an increase in the number of monkeys converting to positive status and the discovery of an indeterminate status demonstrated that latency of B-virus in the rhesus may have the potential to defeat an eradication attempt not conscientiously pursued.