Non-mydriatic retinal photography was offered as a screening service to 37 general practitioners providing diabetes care in their practices. Of 84 patients photographed, 22 had appearances of diabetic retinopathy and these were compared with 25 of the remainder without retinopathy. In only seven of 11 patients with maculopathy or proliferative retinopathy had this been detected by their GP and, likewise, only six of 11 cases of probable background retinopathy had been detected. The mean annual examination rate in general practice was 33 (95% Cl 18-47)%. Of the 18 cases in whom action in response to recommendations for follow-up or referral could be ascertained, 15 (83%) had had the recommendations implemented. Thus, despite the potential risks of false-negative screening using non-mydriatic retinal photography, the technique may improve the comprehensiveness of screening in patients under the care of their GPs.