The invention provides a high-performance wide-angle zoom lens system which has a zoom ratio of 2 or more and an angle of view of 65.degree. or more at the wide-angle end and comprises a reduced number of lenses, and so is favorable for reducing the size, weight, and cost of a camera used therewith. This zoom lens system comprises a first lens group G1 of negative power, a second lens group G2, a third lens group G3 of positive power and a fourth lens group G4 of negative power, with the space between the respective lens groups being varied for zooming. The first lens group G1 consists of a negative lens alone, the second and third lens groups G2 and G3 include one independent negative lens and two positive lenses in all, and the fourth lens group G4 comprises one negative lens or alternatively two lenses, positive and negative.