Three new phenotypes of human erythrocyte acid phosphatase (ACP1) have been detected and found to be unique by direct comparison with previously identified ACP1 variants. One of these new electrophoretic variants, labeled as ACP1FA, has been detected in the Hispanic population of California. The electrophoretic variants identified as ACP1GA and ACP1GB have been detected in a black family in North Carolina. A family study has shown that ACP1G is transmitted as an allele of ACP1.