The objective of this study was to investigate the comparative macro- and microscopical features and proximate compositions of five different strains of Pleurotus ostreatus, commercially cultivated in India. All the strains vary among themselves in terms of their pileus size, colour and Q value of basidiospores etc. which is also evident from the cluster analysis plot. The size of the basidiospores among strain no. Pl-560, N2 and Pl-800 were quiet larger than the remaining strains viz. Pl-350 and Pl-500. Total amount of protein, carbohydrate, fat, crude fibre, moisture as well as mineral contents of five different strains were determined. Proximate compositions of dried mushrooms showed significant variations. Among five strains, strain no. Pl-560 was rich in protein, crude fibre and amino acid content. © RJPT All right reserved.