Several bacterial isolates were isolated from Dakahlia and Damitta Governorates. The isolates were purified, identified and tested for PHB production. The tested isolates were 17 isolates of Azotobacter chroococcum, 8 isolates of Azospirillum lipoferum, 22 isolates of Alcaligenes eutrophus, 3 isolates of A. latus, 3isolates of Bacillus subtilis, 2isolates of B. cereus, 5 isolates of B. megaterium, 2 isolates of B. coagulans, 3 isolates of B. polymexa, 4 isolates of B. thuringiensis, 2 isolates of Pseudomonas fluorescens, 2 isolates of P. putida, 2 isolates of P. alcaligenes, 2 isolates of P. aeruginosa, 4 isolates of Rhizobium leguminosarim, 2 isolates of R. meliloti, one isolate of R. japonicum and 12 isolates of Streptomyces albus.Also, the occurrence of alginate in different isolates of Azotobacter and Pseudomonas were investigated. All isolated strains proved to be PHB producers. The amount of PHB produced by Bacillus isolates varied from 0.02 to 0.16 g/l, while by Azospirillum isolates the PHB amounts ranged from 0.12 to 0.58 g/l. Using Rhizobium isolates, the highest amount of PHB (0.36g/l) was produced by R. leguminasarim No 3 , while the lowest amount (0.06 g/l) was obtained by R. leguminosarim No 2. Usig two media, Alcaligenus eutrophus No. 20, seemed to be the most active PHB producer among all Alcaligenes isolates (0.52 g/l). By Pseudomonas isolates, Pseudomonas fluorescens No. 2 produced 0.30g/L of PHB while P. aeruginosa No. 2 produced 0.10 g/L. Generally the isolate of Azotobacter chroococcum No. 16 showed the highest values. The cell dry weight, PHB concentration and the yield of PHB were 2.28 g/l, 0.78 g/l, 34.21%, respectively. And the highest amount of alginate concentration (g/l) was 0.44 by Azotobacter chroococcum No. 14.