All cases of transient erythroblastopenia in children less than 10 years of age, diagnosed in Sweden during the years 1987-89, were identified. Almost all (51/53) were less than 3 years of age. In this group, the incidence was 4.3/100 000, which is the same as that of acute lymphatic leukaemia. No geographical, but a possible temporal, cluster was seen in 1989. The anaemia was severe in some cases; haemoglobin concentration was less than 40 g/l in 8 of 53 children. Thrombocytosis and neutropenia were common and were attributed to high endogenous erythropoietin activity. Thirty-seven of 53 children were given a blood transfusion. All children recovered and no complications or relapses were seen. Transient erythroblastopenia of childhood is a benign disease, and it is important to make a correct diagnosis to prevent unnecessary anxiety for leukaemia or aplastic anaemia.