To determine whether infants who receive routine childhood immunizations while on chronic peritoneal dialysis (CPD) develop protective antibody levels/titers, we measured antibody levels/titers in infants vaccinated with diphtheria/tetanus/pertussis (DTP) and measles/mumps/rubella (MMR) while on CPD. Eight CPD patients (median age 19 months, range 9-39 months) had measurement of antibody to diphtheria and tetanus toxoids. Seven of the 8 (88%) had protective levels of IgG antibody to both toxoids. The single patient who did not have protective antibody to either diphtheria or tetanus had a low total serum IgG. However, 3 other patients who had low IgG had protective antibody levels. Serial measurements of antibody to tetanus and diphtheria were obtained in 3 of the 8 patients. All maintained protective levels to both diphtheria and tetanus toxoids for as long as 24 months postvaccination. Antibody to rubella was also measured in 5 CPD patients (median 29 months, range 19-39 months), and all had protective antibody titers despite the fact that 3 had low total serum levels. In conclusion, most but not all infants immunized while on CPD have protective antibody levels/titers to diphtherial, tetanus, rubella. Alteration of the routine schedule for immunizations does not appear to be necessary. However, periodic measurements of antibody may be indicated, particularly to live vial vaccines, prior to transplantation.