Abstract. The purpose of this study was to conduct a convenience study for brucellosis prevalence in dairy-producing animals in northern Ecuador. In total, 2,561 cows and 301 goats were tested. Cattle sera were tested using the Rose Bengal card antigen test (RBCT), yielding an overall apparent prevalence of 5.5% (95% confidence interval [95% CI] = 4.7-6.5%) and true prevalence of 7.2% (95% CI = 6.0-8.5%). Prevalence varied by herd size and was highest in larger commercial herds. Polymerase chain reaction was used to test goat milk and lymph nodes, resulting in 9% and 8% positivity, respectively. The RBCTs from goat sera yielded an adjusted true prevalence of 17.8% (95% CI = 6.2-44.2%). Our findings are similar to other overall prevalence estimates for dairy herds but show higher prevalence in commercial herds compared with small groups (less than five animals). We also identify urban milking goats living in metropolitan Quito as a potential source of zoonosis.Brucellosis is a chronic infection caused by an intracellular bacterium, which affects almost every organ system of the body.