Prevalence of antibodies to Toxoplasma gondii was investigated in 673 domestic dogs from northeastern Portugal, using the modified agglutination test (MAT) with 1∶20 as cutoff for seropositivity; antibodies were found in 256 dogs (38.0%). Differences between seroprevalence levels in males (36.7%) and females (41.8%) and between pure-breed (42.1%) and mixed-breed dogs (35.2%) were not statistically significant. Multiple logistic regression analysis identified age above 12 mo (odds ratio [OR]  =  4.0), chance of eating birds or small mammals (OR  =  4.0), housing exclusively outdoors (OR  =  1.5), home-cooked meals (OR  =  3.0), and eating raw meat or viscera (OR  =  7.7) as risk factors for the canine T. gondii infection. Some control measures are suggested based on these findings.