A trial was performed to evaluate efficacy of Coccivac-B ^® versus Sacox 60^®. Cobb x Cobb broilers were obtained and grown to 48d. Birds were vaccinated (Coccivac-B^® ; V), given daily dose of salinomycin (Sacox 60^®; S), or given no coccidiosis treatment (Control; C). Challenge periods were initiated on days 14; 21; 28; 35; and 42 lasting 6 days. Birds were challenged with either coccidiosis oocysts (+) or none (-) creating 2 x 3 factorial with 6 treatment x challenge groups: C+; C-; S+; S-; V+; V-. Broilers were observed for weight gain, feed consumption, oxygen consumption, and carbon dioxide production. After challenge period, lesion scores and body composition were obtained. V birds experienced depressed performance due to coccidial challenge of vaccine early, but rebounded and surpassed the previously superior S birds after their salinomycin was withdrawn on day 35. C birds were negatively impacted by challenge throughout the trial.