Efficacy of virginiamycin (22 mg/kg) in combination with no drug, amprolium, carbarsone, halofuginone, or monensin, was studied. Male and female turkeys were raised to market age in five experiments conducted from 1983 to 1987. Body weights and feed:gain responses to virginiamycin for males and females were positive and significant (P less than .05). Virginiamycin resulted in mean 5.2 and 6.3% body weight responses and 3.3 and 2.2% feed:gain responses for males at 19 or 20 wk of age and for females at 16 or 17 wk of age, respectively. Mortality rates were low in all studies, and were not influenced by virginiamycin. In a processing study, virginiamycin in combination with halofuginone did not affect shrinkage, yield, or market grade. Feed was utilized by males and females 3.9 and 3.0%, respectively, more efficiently than expected with dietary virginiamycin, compared with results predicted by a simulation modeling technique. Profitability was considerably greater with dietary virginiamycin using actual data than with simulated feed consumption data.