Monoclonal antibody molecules of therapeutic finished products could have variations due to their charge variants. Changes of charge profile could alter drug stability bioactivity and/or induce harmful immunogenicity. Therefore each batch should contain a consistent charge variant profile. This study was conducted to analyse charge heterogeneity of 14 brands of therapeutic monoclonal antibodies registered in Thailand using cIEF technique. The electropherogram results of all products showed 3 isoforms and complied with their reference material isoforms. Their pi range was within 7-10