Aims: An experiment was conducted to investigate the comparative efficacy of two probiotics of different origins (yeast and bacterial based) on the growth performance and carcass characteristics of broilers chicken.
 Place and Duration of Study: The study was conducted at Krishi Vigyan Kendra, Purnea between January, 2020 to March, 2020.
 Methods: Two hundred and forty, day old chicks were kept and were randomly divided into 4 groups (A, B, C and D) and each group had 2 replicates of 20 chicks. Four (A, B, C and D) iso-caloric and iso-nitrogenous (ME 3000 kcal/ kg and CP 21.56%) broiler starter and finisher (ME 3000 kcal/ kg and CP 18.75%) diets were formulated containing Saccharomyces cerevisiae, 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.
 Results: A significant (P<0.05) effect was observed on overall performance of the birds fed diet containing probiotics. Probiotics in feed at 0.2% Saccharomyces cerevisiae supplementation improved body weight gain (+12.7%), feed intake (3.8%) and feed conversion efficiency (-8.7%) compared with the control diet. Among groups, no significant differences were observed in carcass traits but highest dressing percentage was recorded in group-B followed by group-C than group-D and lowest in control group.
 Conclusion: The result indicated that the addition of probiotics in feed containing 0.2% Saccharomyces cerevisiae improved broiler growth performances and it is beneficial to be used as supplement in feed of broiler chickens.