Samples from 378 Chinese and 259 Malay blood donors in Singapore have been studied for electrophoretic variants in 13 red cell enzyme systems and for abnormal haemoglobins. Variants were detected in 8 of the enzyme systems, and the frequencies were polymorphic for acid phosphatase, 6 phosphogluconate dehydrogenase phosphoglucomutase (locus 1) among both Chinese and Malays, and for adenylate kinase also among Malays. Rare variants were detected in the phosphohexose, NADH diaphorase and lactate dehydrogenase systems. A new GPGD phenotype and three new LDH phenotypes have been described. Electrophoretic variants of haemoglobin were more frequent among Malays than among Chinese.