OBJECTIVES Retrospective data suggest that a wide pulmonary annulus after Fallot repair aggravates pulmonary regurgitation. Therefore, since 1997, in our institution transannular patch enlargement was only intended for patients with a native pulmonary annulus z-score less than -4. If transannular patching was needed, enlargement was aimed to diameters within the range of a z-score of -2. We sought to determine whether this strategy of restrictive enlargement of the pulmonary annulus was adequate to reduce transannular patch rate and to limit pulmonary annulus width without increased right ventricular pressure load. METHODS Two-hundred-and-sixteen Fallot patients were retrospectively analysed. Ninety-eight patients underwent repair between 1997 and 2006 adhering to our uniform strategy (Group 1). One hundred and eighteen patients were operated between 1977 and 1996 without a uniform strategy (Group 2). Transannular patch rate, native and postoperative pulmonary annulus z-score, postoperative right ventricular outflow tract velocity on echocardiography and early reoperation rate for right ventricular outflow tract obstruction were analysed in both groups. RESULTS Compared to Group 2, patients in Group 1 were younger at repair, transannular patch rate was significantly reduced (32 vs 68%, p<0.0001) and postoperative pulmonary annulus diameters were smaller (z-score -2.1+/-1.5 vs 0.0+/-3.1, p<0.0001). However, no difference in right ventricular outflow tract velocity (2.4+/-0.8 vs 2.2+/-0.8m/s; p=NS) or the incidence of early reoperation for right ventricular outflow tract obstruction was found between the groups (3/98 vs 1/118; p=NS). CONCLUSION Restrictive enlargement of the pulmonary annulus at Fallot repair lowers transannular patch rate, limits the postoperative width of the pulmonary annulus but does not result in increased right ventricular pressure load or reoperation rate for residual right ventricular outflow tract obstruction. A limitation of postoperative pulmonary regurgitation can be expected when the extent of pulmonary annulus enlargement at repair is limited.