Objective To study the effect of Tongmai Tangyanming Capsule on flash electroretinogram （F-ERG） and its oscillatory potentials （OPs） in diabetic retinopathy （DR） patients. Methods Totally 84 eyes of DR patients were randomly divided into treatment group of 43 eyes and control group of 41 eyes. Blank group was established by gathering 40 eyes of even-aged healthy persons. Tongmai Tangyanming Capsule was used in treatment group. The amplitudes and peak latencies of F-ERG and its OPs in three groups were detected and contrasted before and after treatment. Results The amplitudes of F-ERG and its OPs shortened but peak latencies prolonged significantly in DR patients as compared with blank group （P<0.01）. The total amplitude of OPs and amplitudes and peak latencies of F-ERGa

F-ERGb and each wavelet of OPs in treatment group rebounded after treatment

resulting in significant differences with before treatment and control group （P<0.01）. Conclusion Tongmai Tangyanming Capsule can improve retinal function of DR patients obviously.