To find a suitable surfactant for enhancing the solubility of fatty acid, some nonionic surfactants including Tween 20, 40, 60, 80, 85; poly-ethylene glycol 200, 300, 400, 600; di-ethylene glycol di-methyl ether (diglyme), Triton X-100, tetrahydrofuran (THF) and dioxan were added to the fermentation medium (with or without palmitic acid) and their effects were studied on the morphology of Saccharopolyspora erythraea and erythromycin production. Tween 20 and Triton X-100 lysed the hyphae, but in the media containing other surfactants, the hyphae remained in a vegetative form. PEG 300, Tween 40 and THF had neither negative nor positive effect on the erythromycin production. But, addition of Triton X-100 and dioxan to the fermentation medium significantly decreased the concentration of erythromycin, 9.9 and 1.3 times less than that of control, respectively. In the media containing PEG 200, PEG 400, PEG 600, Tween 60, Tween 80, Tween 85 and diglyme, erythromycin concentration was 1.3, 1.5, 2.0, 1.4, 1.4, 1.3 and 1.3 times higher than that of control, respectively. Production of erythromycin in the palmitic acid containing medium was 1.62 times lower than that of control. However, the effect of palmitic acid on the erythromycin production was different when surfactants were added to media. Erythromycin production in the media containing palmitic acid plus PEG 400 and palmitic acid plus PEG 600 was more than that of palmitic acid containing medium (without any additional surfactant). However, erythromycin con-centration in the media containing Tween 40, 60, 80 and 85, THF and diglyme was less than that of medium containing palmitic acid (without any surfactant).