['We conducted a prospective study to determine the role of alpha1-antitrypsin (alpha1AT) deficiency in the pathogenesis of neonatal cholestasis and other childhood liver diseases in a multi-ethnic Southeast Asian population.', 'Prospective patients with neonatal cholestasis (group 1), other liver diseases (group 2) and children with other medical conditions (group 3) referred to the Paediatric Unit, University of Malaya Medical Centre, Malaysia, from May 2002 to June 2005, were screened for alpha1AT level and phenotype. alpha1AT level below 80 mg/dL was considered as low.', 'Of the 114 patients (group 1, n = 53; group 2, n = 42; group 3, n = 19) screened, seven patients (6% of total; group 1, n = 1; group 2, n = 4; group 3, n = 2) had a alpha1AT level below 80 mg/dL. All had marginally low level (range 57-79 mg/dL), but none had a clinical diagnosis of alpha1AT deficiency. One patient had PiZ- heterozygous phenotype (alpha1AT level 217 mg/dL) while another patient had PiMS heterozygous.'] Is alpha1-Antitrypsin deficiency an important cause of childhood liver diseases in a multi-ethnic Southeast Asian population?