In this study, 2 slow growing broiler genotypes (SG1 and SG2) slaughtered at 49 days of age were compared with a fast growing commercial genotype slaughtered at 42 days of age (FG1) or 49 days of age (FG2) with respect to fattening performance, carcass characteristics and some economic parameters. The study was carried out in 2 periods and 260 chicks from each genotype in each period (a total of 1560 chicks; 260 x 3 x 2) were used. Ten replicates of chicks from each genotype were reared on litter system. Live weight, feed consumption, feed efficiency and mortality in groups (SG1, SG2, FG1, FG2) were determined throughout the production periods, while slaughter and carcass traits were determined at the end of production periods. Cost, efficiency and technical efficiency scores were calculated by using production expenses and meat sale prices. Stochastic frontier analysis (SFA) was used to estimate the technical efficiency scores of groups. SG1 and SG2 genotypes reached to slaughtering live weight (2.0-2.5 kg) at 49 days of age, and the feed consumptions of these 2 genotypes were similar to the consumption of F1. The breast ratio was higher in FG1 and FG2, whereas the thigh ratio was higher in SG1 and SG2. The highest relative profit was determined in FG1 genotype and FG2, SG2 and SG1 followed this genotype, respectively. The technical efficiency scores of SG1, SG2, FG1 and FG2 were 0.9632, 0.9639, 0.9664 and 0.9699 (P<0.05), respectively. The mortality in FG1 (5.00%) and FG2 (6.54%) can be interpreted as significant losses, although net and relative profits of these groups were superior to SG1 and SG2. At the end of 49 days, the mortality in SG1 and SG2 genotypes occurred as 1.15% and 2.69%, respectively (P<0.05). Despite the fact that SG1 and SG2 genotypes reached to slaughtering weight at 49 days of age, they were advantageous due to their lower mortality levels.