The objective of this study was to evaluate the relationship between body mass index corrected (BMIc) for empty body weight and chemical components in hair sheep lambs. Thirty-eight weaned Pelibuey lambs (21 males and 17 females, with an average weight of 10.64 ± 2.46 kg) were used. The carcass was dissected into muscle and fat and ground together. The viscera and blood were mixed, ground, and one sample was collected from each animal. Crude protein and fat were determined in carcass and viscera samples. Correlation and regression were used to estimate the relationships between body composition and BMI. The correlation between BMIc and carcass crude protein (CCP) and visceral crude protein (VCP) was 0.80 and 0.50, respectively (P < 0.0001). BMIc showed a correlation of 0.71 and 0.70 with carcass fat (CF) and visceral fat (VF), respectively (P < 0.0001). The R² values ranged from 0.52 to 0.97 for equations involving BMIc and body chemical composition. For carcass chemical components, CCP, CF and CE (carcass energy) with BMIc and R² ranged from 0.64 (RSD: 0.10 kg) for CCP, 0.53 (RSD: 0.16 kg) for CF to 0.62 (RSD: 7.98) for CE. Visceral composition and BMIc had R² values ranging from 0.96 for VCP (RSD: 0.05 kg), 0.52 for VF (RSD: 0.09 kg) to 0.55 (RSD: 4.34 kg) for VE (visceral energy). BMIc can be used to moderately predict body chemical composition in weaned Pelibuey lambs.