The Pegomya hyoscyami species complex, which contains the economically important beet and spinach leaf-miners, is defined and taxonomically revised. Four distinct species are recognized by differences in the adult morphology of both sexes: Pegomya betae (Curtis), P. cunicularia (Rondani), P. exilis (Meigen), and P. hyoscyami (Panzer). A key for identification, diagnoses, figures of the male and female genitalia, and distribution records are provided. The nomenclature adopted here is a result of a critical review of 21 relevant species-group names. Five lectotypes are designated and four new synonymies are established; five names are considered nomina dubia and one is a nomen nudum. All four species occur in Europe, whilst only two are known from North America (betae, hyoscyami) and Japan (cunicularia, exilis).