Twenty Zebu culling commercial cows aged between 42 and 72 months, from Piedemonte Llanero used for a study of prediction of carcass weight using realtime ultrasound (RTU). Cows fattened on pasture, were weighed and sent to the slaugtherhouse for dressing. Twelve hours of pre-slaughter each cow were taken by ultrasound measures: rib eye area (REA), back fat thickness (BFT) at the 12-13 rib site, depth of gluteus medius (DGM) and thickness fat at the rump (TFR). Furthermore, it was the body condition score (BCS) and temperament scores (TS). Post-slaughter, the information was collected from the weight of hot and cold carcasses (WHC and WCC). Statistical analysis included: descriptive statistics, Pearson correlations, multiple regression analysis between measurements in vivo and postmortem for the prediction of carcass weight. The cows had an average weight live (WL) of 408.70 kg. REA, BFT, DGM and TFR averages for the cows were 48.87 cm2, 4.16 mm, 69.86 mm and 7.60 mm, respectively. BCS average was 5.5. WHC and WCC averages were 208.19 kg and 198.55 kg, respectively. We found moderate correlations (p<0.05) between REA with BCS and REA with PCC postmortem, which could be quantitative indicator for production. REA and EG measures at the rib site showed no correlation with the carcass weight. We also found a moderate correlation (p <0.05) between the BSC and WHC, which could be a useful visual tool to estimate the fat thickness in cows before dressing. Measures such as REA and WL could be used to reasonably predict the WHC Zebu cows culling.