Abstract: Toxocara canis is one of the most common parasites living in the intestine of domestic and stray dogs. A dog eliminates thousands of eggs into the environment that are potential etiological factor for human toxocariasis. The present study was undertaken to determine the prevalence of T. canis in stray dogs in Mazandaran, Iran. In this cross-sectional study, during the period from April to September 2007, 50 young and adult stray dogs were collected by shooting from urban areas of Sari city, Northern Iran. They were necropsied and the gastrointestinal tract was opened. Recovered parasites were fixed in alcohol and stained in carmine. Faecal specimens were also examined by the formalin ether concentration method. A total of 27 adult and 23 young dogs were examined with 11 adults (40.7%) and 19 youngs (82.6%) being infected with T. canis with an overall prevalence of 60%. There were significant differences in the prevalence of infection between adult and young dogs (p = 0.003). There were no significant differences in the prevalence of infection between male and female dogs (p>0.05). Considering the high prevalence of this zoonotic parasite and its hygienic significance in causing human toxocariasis, particularly in children, plus the lack of control of stray dog populations, there is a need to improve personal and food hygiene as well controlling stray dogs in these urban areas.