An experiment was conducted to investigate the comparative efficacy of two probiotics of different origins (yeast and bacterial based) on the growth performance, immune response, carcass characteristics and nutrient digestibility of broilers. One hundred and twenty day old chicks were purchased from local hatchery and were randomly divided into 4 groups and each group had 3 replicates of 10 chicks. Four (A, B, C and D) iso-caloric and iso-nitrogenous (ME 2850 kcal/ kg and CP 20%) broiler starter and finisher (ME 2880 kcal/ kg and CP 18%) diets were formulated containing yeast (Saccharomyces Cerevisiae), toyocerine (Bacillus cereus toyoi) and mixture of both @ 0.2 % except group A which was control. Birds were raised for first week on commercial diet. Broiler starter and finisher diets were fed from 8-28 and 29-42 days, respectively. A significant (P<0.05) effect was observed on overall performance of the birds fed diet containing probiotics (yeast and bacteria). Growth performance, immune response, carcass characteristics and nutrient digestibility were significantly (P<0.05) higher in birds fed diet (B) containing yeast (followed by those fed diet (C) containing toyocerine  and those fed diet (D) containing both yeast and toyocerine.