Differentiation of some abnormal haemoglobins, such as Hb C, O-Arab, Agenogi, E, O-Indonesia, C-Harlem, and Siriraj, is difficult and quantitation of the various fractions is impossible with cellulose acetate electrophoresis. The authors report 13 cases of Hb C, 10 of Hb O-Arab and 5 of Hb Agenogi whose haemoglobin fractions were quantitated by HPLC during a thalassaemia screening programme. Hb F was determined by both Betke's method and HPLC. Analysis of data by linear regression demonstrates that the methods furnish overlapping results. Our findings show that HPLC is a rapid and easily reproduced method which allows quantitative and qualitative discrimination of the various haemoglobin fractions, making it a valid tool in screening programmes for haemoglobinopathies.