This study aimed to predict the hairiness of cotton/polyester blended rotor yarns using blend ratios and yarn count as predictor variables. A simplex lattice design with two replications at each design point was constructed to determine the combinations of mixture ratios of the fibre types. Cotton/polyester blended slivers were used to produce rotor yarns with five different counts on a laboratory-type rotor spinning machine (quickspin). Mixture-process crossed regression models with two mixture components and one process variable (yarn count, linear density) were built to predict hairiness properties. All statistical analysis steps were implemented, using Design-Expert statistical software.