The prevalence of helminth species in stray dogs, from the capital city of the state of Queretaro, was evaluated. A total of 378 dogs were captured and examined for the presence of helminths from January to December 2008. The results showed that 275 (72.8%) of examined dogs were infected with one or more helminth species. Single infections were observed in 139 (50.5%) of infected dogs and 136 (49.5%) harboured mixed infections. Out of the 378 dogs examined, 208 (55.2%) presented nematodes and 182 (48.1%) cestodes. The prevalences (confidence interval) and mean intensities of infection ( ± SD) of nematodes and cestodes encountered were: Ancylostoma caninum 42.9% (37.9–47.8) and 22.1 ( ± 34.3); Toxocara canis 15.1% (11.8–19.0) and 8.3 ( ± 15.0); Spirocerca lupi 4.5% (2.7–7.1) and 3.9 ( ± 4.8); Toxascaris leonina 2.3% (1.1–4.5) and 4.8 ( ± 3.5); Physaloptera praeputialis 1.9% (0.8–3.8) and 9.7 ( ± 14.9); Dirofilaria immitis 1.3% (0.4–3.1) and 5.6 ( ± 2.1); Oslerus osleri 0.3% (0.0–1.6) and 5 ( ± 0.0); Dipylidium caninum 44.9% (40.0–50.0) and 18.1 ( ± 27.7); Taenia spp. 6.9% (4.7–9.9) and 6.9 ( ± 7.1). There were no significant differences in prevalences observed either between female (68.5%) and male (76.8%) or between young (70.6%) and adult (74.2%) animals. No differences were observed in the ANOVA test for the mean intensity of infection of any of the parasites (P>0.05).