The results of CE studies of solid inclusion complexes of chlorambucil (CHL) and trimethyl-beta-cyclodextrin (TM-beta-CD) are presented. Chlorambucil has low stability in aqueous solution, so the formation of complexes with beta-CD is a good way to improve its stability and dissolution. The experimental results confirm the existence of inclusion complexes. CE can differentiate free CHL from CHL-TM-beta-CD complexes due to their different electrophoretic mobilities.