The aim of this prospective, randomized clinical trial was to compare the efficacy of parenteral nutrition (PN) in adult bone marrow transplant (BMT) patients on a continuous (CON) versus a cyclic (CYC) regimen. Twelve patients received CON PN and 12 CYC PN. The groups were homogeneous. CON PN received 27.2 +/- 3.7 kcal/kg/day and for CYC PN 25.9 +/- 4.2 kcal/kg/day (P= 0.45). The duration of PN was 20.4 +/- 7.9 days and 27.3 +/- 13.4 days respectively (P = 0.14). There were no differences between initial and final body weights, either within or between groups. The initial pre-albumin levels were 16.1 +/- 7.5 mg/dl and 20.1 +/- 4.9 mg/dl in CON PN and CYC PN, respectively (P= 0.22), and these were maintained throughout the study. Blood glucose levels did not differ between groups. Measures of liver function were moderately increased, but with no significant differences between groups. There were no significant differences regarding the efficacy of PN or the appearance of complications between CON PN and CYC PN in patients with BMT.