The effects of solvent type and concentration, solid/liquid ratio, extraction time and repeated extraction on recovery ofkeratinase from solid-state fermentation (SSF) of chicken featherby a local Streptomyces sp. NRC 13S were investigated in orderto establish the experimental conditions for keratinase yield.Among solvents tested, 0.5% (v/v) glycerol was the best. Box-Behnken design was used to investigate the effect of relevantvariables on keratinase recovery. The factors investigated weresolid/liquid ratio (1:1.66-1:6.66g/mL), glycerol concentration (0.5-5% v/v) and repeated extraction (1-5 cycle). The resultsshowed that the maximum recovery of keratinase (6933.3 U/gfs)was obtained using 0.5 (v/v) glycerol as extracting solvent, in asolid /liquid ratio of 1:5 and three extraction cycles.