A prospective study of Chinese patients with megaloblastic anaemia was conducted at the Pamela Youde Nethersole Eastern Hospital from 1 May 1994 to 31 August 1997. Megaloblastic anaemia was diagnosed in 57 patients, 52 of whom were eligible for further evaluation. The median age of these 52 patients was 73.5 years and the male to female ratio was 1.08:1. The serum cobalamin level (median, 56 ng/L) was low in 46 (86.5%) patients. In five (9.6%) patients, both serum cobalamin and red blood cell folate concentrations were low. Isolated low red blood cell folate level was demonstrated in one (1.9%) patient. Serum antibodies against intrinsic factor and gastric parietal cells were detected in 32 (61.5%) and 26 (50.0%) patients, respectively; 19 (36.5%) patients had both types of antibody. The aetiology of megaloblastic anaemia included pernicious anaemia in 39 (75%) patients, postgastrectomy vitamin B12 deficiency in five (9.6%) patients, and nutritional deficiency in two (3.8%) patients; the cause was undetermined in six (11.5%) patients.