Streptomyces sp. GHB5 was isolated from Egyptian soil, optimized for polygalacturonase production and identified as Streptomyces sp. GHB5 by 16S rRNA sequencing and submitted to gene bank data base with accession number LC405930. Submerged fermentation was carried out using Streptomyces sp. GHB5 for polygalacturonase production. Different physico-chemical and nutritional factors were optimized for maximum polygalacturonase production. Results revealed that the maximum polygalacturonase production come to 34.09 U/mg specific activity. The best obtained conditions were achieved using broth medium with working volume of 20 % (v/v), containing 1.5% (w/v) lemon peel and 0.28% (w/v) potassium nitrate with initial medium pH of 7.5, when incubated at 30°C and 180 rpm for 6 days with an inoculum size of 4% (v/v) of 5 days inoculum age.