The book is a diploma thesis on fruit flies. Fruit flies are not well known in Burundi even by fruit growers. Unfortunately damages caused by fruit flies are seen in many locations where fruits are grown. In addition some exotic species such as Bactrocera dorsalis and Zeugodacus cucurbitae are now present on burundian territory. This book is the result of a research conducted in the western region of Burundi with the aim of making an inventory of fruit flies present in this part of Burundi. Via this research 18 species of fruit flies have been identified. Seven of these species are newly identified in Burundi.