Background: Allogeneic haematopoietic stem-cell transplantation (allo-HSCT) is associated with frequent and severe malnutrition, which may contribute to transplant-related morbidity. While both enteral nutrition (EN) via a nasogastric tube and parenteral nutrition (PN) are effective, it remains unclear what is the optimal method of nutritional support. Aims: We propose to compare the impact of EN versus PN on early outcome after allo-HSCT. Methods: We evaluated the effect of initial nutritional support with EN versus PN on early outcome in 56 patients who required nutritional support after first allo-HSCT for haematological malignancies in our centre. Patients were offered EN but could decline and chose to be treated by PN. Results: Twenty patients received myeloablative conditioning and 36 received reduced-intensity conditioning. Twenty-eight patients received EN and 28 received PN. Compared with PN, EN was associated with a lower median duration of fever (2 versus 5 days; p<0.01), a reduced need for empirical antifungal therapy (7 versus 17 patients; p < 0.01), a lower rate of central venous catheter replacement (9 versus 3 patients; p = 0.051) and a lower rate of transfer to intensive care (2 versus 8 patients; p = 0.036). The early death rate (<100 days) was the same in both groups (14%). Conclusions: Compared with PN, EN was associated with a lower risk of infection in allo-HSCT, without an increase in the incidence of graft-versus-host disease.