The prevalence, molecular characteristics and haematological study of thalassaemia in lower northern Thailand were determined in 1,000 pregnant women who attended an antenatal clinic at Buddhachinaraj Hospital, Phitsanulok, Thailand. A complete blood count, Hb A2 quantification and DNA analysis were performed. The results exhibit the prevalence of α10-thalassaemia, α+-thalassaemia and β-thalassaemia as 5.3%, 14.6%, and 1.4%, respectively. Regarding the abnormal haemoglobins, the prevalence of HbE, Hb Constant Spring (CS), and Hb Pakse (PS) was 24.2%, 5.3%, and 0.1%, respectively. MCV and MCH were significantly different between thalassaemia carriers and normal subjects. Since the MCV of less than 75 fl and MCH of less than 25 pg were found in all α0-thalassaemia subjects, these parameters could be used for α0-thalassaemia screening. Copyright © Hellenic Society of Haematology.