Bone-marrow transplant (BMT) patients are severely immunocompromised immediately after the procedure and they are commonly nursed in strict protective isolation to reduce the risk of both infection and graft-versus-host disease (GvHD). We have studied a consecutive series of patients to see whether protective isolation is of benefit as prophylaxis against infectious complications of BMT. 50 consecutive patients who had malignant disease and received their first BMT from siblings or unrelated donors were nursed in standard single rooms with visitors instructed to wash their hands. A subset of 20 patients living locally spent a median of 25 days in hospital after BMT; they also spent some time at home on a median of 8 days before engraftment and 3 patients went home on more than 90% of their hospital days. 16 patients (32%) had positive bacterial cultures and/or focal infection. Gram-positive bacteraemia was found in 12 subjects (24%) but there were no gram-negative or deep fungal infections. Grade II or III acute GvHD developed in 17 patients (34%). There were no deaths from infection or acute GvHD. Transplant-related mortality was 6% in the first 100 days and 18% overall with a median follow-up of 22 months. Our mortality data compare favourably with those from institutions with strict isolation procedures. We conclude that BMT may be safely completed in some institutions without either protective isolation or the need to confine patients continuously in hospital.