Abstract: This work is to compare the effects ofremoving fish odour and bitter inprotein hydrolystaesof tilapia Oreochromis niloticus wastes by different microorganisms fermentations, in which lactic acid bacteria such as Streptococus thermophilus, Lactobacillus helveticus, L.bulgaricus and yeasts were used. The removal potency of fish odour and bitter was evaluated by sensory test. The results indicated that the effect of fish odour removal fromprotein hydrolystaes by lactic acid bacteria fermentation was better than by yeasts, in which the best microorganism was S.thermophilus. The optimal conditions for S.thermophilus fermentation were 42℃ for temperature and 9 h for time with 10%inoculation volume. There was little effect to remove bitter taste from protein hydrolystaes by microorganism.