This prospective study compares combined phacoemulsification and trabeculectomy (phaco-trab) to conventional phacoemulsification (phaco) in patients with coexisting cataract and open angle glaucoma. Twenty eyes were randomly assigned to either phaco-trab or phaco and followed for 12 months. Postoperatively, IOP decreased significantly in both groups, but patients with the combined procedure had fewer early IOP-elevations and significantly less medication. Visual acuity improved equally in the two groups.