The aim of the present study was to test a possible way of monitoring cattle carcass classification using a statistical approach. For that purpose the analysis of covariance (ANCOVA by SAS) was used with the fixed effect of the abattoir, carcass weight (as a covariate) and their interaction. The analysis was based on the relationship between carcass weight and conformation or fatness grades. We tested if the regression lines of individual abattoirs differ from the average. The analysis comprised data for young bulls of Simmental breed slaughtered in Slovenia in the period from 2007 to 2010 (52,624 records). Results showed that in many abattoirs the assessment of conformation and fatness deviates significantly from the average, i.e. regression lines for several abattoirs differ significantly from the average (population) line. Differences were more important for the conformation than fatness. The statistical process control using the analysis of covariance can be used for additional monitoring of cattle carcass classification