Dilatation of the urinary tract may be due to vesicoureteric reflux, urinary tract obstruction, or to primary dilatation. In a proportion of patients these factors may coexist. A retrospective review was carried out to estimate the incidence and features of coexisting reflux and obstruction. Our review indicates that the coexistence of urinary tract obstruction and primary reflux is more common than previously reported, occurring in approximately 1 in 20 patients with reflux. Any patients with reflux who has a dilated and/or tortuous ureter must be suspected of having obstruction. This may be ruled out in the majority of cases by a drainage film after a micturating cystourethrogram and the importance of this simple procedure is emphasised.