A historical overview of the leech fauna of Morocco, based on both literature data, museum collections and new material, sampled in more than 100 sites in the Moulouya River basin (eastern region of Morocco), is provided. Twenty species from five families and ten genera are currently known, of which Helobdella europea Kutschera, 1987, is a new record for the country and North Africa as a whole. Herein, we add many new distribution records. The current list will need to be revised as new species distributions are recorded in the region. Notes on the species distribution are given along with comments on their habitat preferences. A concise biogeographic analysis outlines the similarities in the distribution of some species at regional and continental scales. This contribution is intended to provide information concerning the leech fauna of Morocco and is considered a foundation for future studies.