Spleen size, stomatocytosis, macrothrombocytopenia, haemoglobin level, white cell count, and abdominal pain episodes were assessed in a coded study of healthy Mediterranean immigrants to Australia. Spleen size was estimated from a length measurement, L, on a standardized plain abdominal radiograph and expressed both as spleen weight and as a spleen length index, L/square root BSA; the platelet count and size parameters were determined electronically and the presence of stomatocytes was evaluated in stained blood films. In relation to 16 Northern European control women 12 of 25 Mediterranean women had radiographic splenomegaly, 10 had macrothrombocytopenia, 9 had stomatocytosis, but none had episodes of abdominal pain. The median spleen weights of the two groups were estimated as 157 and 247 g with ranges from percentile 2.3 to 97.7 of 75 to 328 and 112 to 669 g. Within the Mediterranean group splenomegaly correlated with macrothrombocytopenia (P less than 0.001) but not with stomatocytosis, haemoglobin values or white cell counts. Thus, mild splenomegaly may be expected in Mediterranean macrothrombocytopenia, Mediterranean stomatocytosis appears unrelated, and all of these apparently benign anomalies may be incidental findings in patients from the Italian and Balkan peninsulas.