We have designed treatment conditions which allow analysis of the coat proteins of bacteriophage T4D+ by high resolution two‐dimensional electrophoresis. The best results were obtained when the mature phage particles were subjected to hypertoniclysis and DNase treatment before solubilization with sodium dodecyl sulfate (SDS). Samples containing 250 ug protein gave the optimum resolution, producing 45 spots as visualized by Coomassie Blue staining. Computerized densitometry measurements showed that these proteins range in relative abundance from less than 0.22% to 11.8% of the total. Copyright © 1981 Verlag Chemie, GmbH