Infectious complications were analysed in 50 consecutive autologous bone marrow transplant (ABMT) patients treated with high dose etoposide and melphalan, 30 of whom also received total body irradiation (TBI). Fever developed in 44 patients and bacteremia was documented in 13 (26%). Patients given TBI had increased susceptibility to bacteremia; 11 of 30 patients who received TBI had positive blood cultures, in contrast to two of the 20 who did not (p = 0.035). In addition, patients who received TBI had significantly more severe diarrhea (p = 0.037) when compared with those who received chemotherapy alone. Thirty-five patients treated with trimethoprim-sulfamethoxazole prophylaxis had a signficantly lower incidence of gram-negative bacteremia (p = 0.024). However, when those patients who received trimethoprim-sulfamethoxazole until neutrophil recovery were analysed alone, those who were also given TBI still had significantly more bacteremia (p = 0.047). Forty-seven patients with follow-up of more than 12 months are available for analysis of varicella zoster (VZV) infections. Of the 29 patients who received TBI, 11 (38%) developed VZV infections, in contrast to one of 18 patients (6%) treated with chemotherapy alone (p = 0.013). These results suggest that addition of TBI to the intensive therapy regimen for ABMT is associated with significantly more bacteremia and late VZV infections.