One hundred and sixty-seven patients subjected to splenectomy on haematological indications were studied. They were grouped into five diagnostic categories: auto-immune disorders (52 patients), Hodgkin's disease (32) lymphoproliferative malignancies (60), myeloproliferative malignancies (18) and miscellaneous (5). The total number of complications and deaths were 42 (25 per cent) and nine (5 per cent), respectively. Infections were the most common complication, occurring in 30 cases and accounting for 59 per cent of all sequelae. Patients with auto-immune disorders had a high frequency of subphrenic left-sided abscesses (5/52). Splenectomy for Hodgkin's disease was associated with a very low frequency of complications. In the 60 patients with lymphoproliferative malignancies left-sided pneumonia was common (9/60). Complications occurred in 56 per cent of the patients with myeloproliferative disorders, the associated mortality rate being 28 per cent. It is concluded that elective splenectomy in haematological diseases seems to be a safe procedure in most patients with the exception of individuals with myeloproliferative malignancies. The high operative risk in this group makes the benefit questionable. In patients with auto-immune disorders the high frequency of subphrenic abscesses indicates that prophylactic antibiotic treatment should be considered.