The aim of this study was to determine the effect of the pre-mating weight and placental characteristics on birth weight. Data were collected from 62 Karayaka ewes and 70 Karayaka lambs. The placental characteristics considered were placental weight, placental area and the number of cotyledons. The Pearson correlation coefficient was used for statistical comparison and the determination of relationships between variables. In addition, correlation coefficients between live weights and placental characteristics were determined. The average birth weight (BW), pre-mating weight (PMW), placental weight (PW), placental area (PA) and cotyledon number (CN) values were 4.37 ± 0.70 kg, 50.22 ± 5.63 kg, 362.51 ± 118.42 g, 994.18 ± 312.76 cm 2 and 56.93 ± 8.06, respectively. BW had positive correlations with PMW (0.147), birth type (BT) (0.643), PW (0.604), PA (0.323) and CN (0.161) ( P < 0.05). BW had negative correlations with maternal age (MA) ( - 0.119 ) ( P < 0.05). PMW had positive correlations with maternal age (MA) (0.237) ( P < 0.05). PMW had negative correlations with S (sex) ( - 0.003 ), PW ( - 0.049 ), PA ( - 0.067 ) and CN ( - 0.080 ) ( P > 0.05).