This project was designed to determine whether a coordinated regional strategy can improve the implementation of national guidelines for screening for retinopathy of prematurity (ROP), and to identify causes for failure of compliance.Retrospective case note audit relating to two periods, 1990-1 and 1994, involving all 17 neonatal intensive care units in the Northern Region of England. Between the two periods, a regional strategy was instituted in an endeavour to improve compliance. Babies born in or admitted to the units during the study periods who were eligible for ROP screening were included. Screening performance was assessed against a standard of 100% compliance with the guidelines. In the second audit period compliance with subsidiary standards was also measured, and reasons for failure were identified.Compliance improved from 47% (262/558) in the first audit cycle to 73% (264/360) in the second. Subgroup analysis in this second cycle indicated better compliance (93.3%) in higher risk babies (< or = 29 weeks' gestational age). Babies transferred between units, discharged home before screening, or who failed to qualify for screening on one of the two defined criteria, were more likely to be missed.A carefully implemented regional approach to screening resulted in a higher uptake for babies most at risk. Simple recommendations are made to achieve further improvement in compliance with the guidelines. The wider implications for screening in other conditions and in other areas and specialties are highlighted.