In this study, the relationship between temperature and humidity levels and live weight losses of day- old chicks in broiler pure lines with different feathering rates were investigated. The research material consisted of 3 female pure-lines (A1: slow feathering, A2: fast feathering, A3: slow feathering) and 2 male pure-lines (B1: fast feathering, B2: fast feathering) used in broiler breeding. The hatching chicks were individually numbered, sex-seperated, live weight determined and vaccinations were performed at 26-28°C temperature and 60-65% humidity levels in hatchery. The chickens from different genotypes were placed in cardboard boxes of 68×49×16 cm size with 3 unit and 150 chicks were used in the male-female mixed in 10 chicks in each unit. The chicks were transported in an air-conditioned vehicle for 9 hours between Eskişehir and Samsun, with an average temperature of 28.8°C and a humidity of 40.8%. When the chicks arrived to barn, weight losses are determined individually during transport. The effect of genotypes and feathering rates on live weight loss was found significant. The highest weight loss was determined 1.6 g and 3.8% in B1 and B2 genotypes equally without gender effect. Also, A2 and A3 genotypes were similar too; genotypes with the lowest weight loss of 0,7 g and 0.8 g and 1.6% respectively. Besides, the live weight loss in genotypes with fast feathering was found 1.3 g and 3.1%, which was significantly higher than the slow-feathering (0.9 g and 2.1%). The weight loss fast-feathering male pure-lines is higher than fast-feathering female pure-lines; it is thought that the increase in the metabolic rate due to the selection for live weight increase and faster depletion of the body reserves may be effective in these lines.