the experiment was conducted to investigate the viability of the production of the edible fungus pleurotus sajor-caju (fr.) singer in substrates in which main source of carbon was the cotton textille mill waste. two substrates compositions were tested: c1 (cotton textille mill waste, wheat bran, plaster and limestone) and c2 (cotton textille mill waste, wheat bran, bean straw, plaster and limestone). a dic experimental design was used, with nine repetitions for treatment and the production data and biological efficiency were analyzed being used the procedure anovag of the statistical package saeg. the cotton textille mill waste improvement, as the main ingredient of the substrate, was shown efficient for the production of the mushroom p. sajor-caju, presenting satisfactory values of productivity (0,56 and 0,55 kg/kg substratum) and biological efficiency (55,76 and 55,39%), respectively for c1 and c2. these results showed us that cotton textille mill waste, could be recommended as less onerous alternative of commercial substrate for the species pleurotus sajor-caju.