Verb suppletion by gender is a typologically rare phenomenon in which phonologically unrelated verb stems are used in accordance with the gender of an argument. By now, only a handful of languages of New Guinea have been convincingly shown to exhibit this phenomenon, which accords with the typological prediction by Bybee (1985) that gender is the least likely category to trigger verb suppletion. This thesis provides a preliminary study of verb suppletion by gender, focusing on mapping out the basic features of the phenomenon and contrasting them to previous findings on verb suppletion. In addition, the different ways suppletion by gender is integrated into the systems of verb agreement are explored, and the possible explanations for how the phenomenon might have emerged are discussed. The thesis finds that despite its typological rarity, suppletion by gender usually affects around two verbs in a language, which is about equal to the number of verbs usually affected by the more common type of verb suppletion by tense and aspect. However, unlike tense and aspect suppletion, there are no clear semantic fields of verbs where suppletion by gender preferably occurs. Moreover, in most of the languages with verb suppletion by gender, there are two genders which are assigned to nouns according to sex for humans or animates, and according to highly opaque assignment rules for non-humans or inanimates. The thesis also finds that while there are different ways verb suppletion by gender can be integrated into the agreement system of a language, the selection of gender-suppletive stems is always conditioned by syntactic principles instead of lexical selection. Lastly, incursion, the standard explanation for verb suppletion, is hard to imagine as the cause for verb suppletion by gender, which highlights the typological rarity of the phenomenon.