Human growth hormone (hGH) is synthesized and stored by somatotroph cells of the anterior pituitary gland and can effect on body metabolism. This protein can be used to treat hGH deficiency, Prader Willi syndrome and Turner syndrome. The limitations in current technology for soluble recombinant protein production, such as inclusion body formation, decrease its usage for therapeutic purposes. To achieve high levels of soluble form of recombinant human growth hormone (rhGH) we used suitable host strain, appropriate induction temperature, induction time and culture media composition. For this purpose, 32 experiments were designed using Taguchi method and the levels of produced proteins in all 32 experiments were evaluated primarily by ELISA and dot blotting and finally the purified rhGH protein products assessed by SOS PAGE and Western blotting techniques. Our results indicate that media, bacterial strains, temperature and induction time have significant effects on the production of rhGH. The low cultivation temperature of 25 degrees C, TB media (with 3% ethanol and 0.6 M glycerol), Origami strain and a 10-h induction time increased the solubility of human growth hormone. (C) 2015 Elsevier Inc. All rights reserved.