The prevalence, incidence and risk factors of infection by Echinococcus granulosus were studied in the domestic and street dogs of Kathmandu, Nepal. Using an ELISA coproantigen test as a screening method, the highest prevalence (5/88 = 5.7%) was seen in domestic dogs from an area of the city used for slaughtering livestock. A prevalence of 1.8% (3/171) was found in domestic dogs seen at eight veterinary clinics distributed around the city. Although none of the 73 street dogs sampled in the ELISA screening survey was positive, three of 20 street dogs killed with poison as part of the city's dog-control programme harboured from one to five adult worms. As none of 99 dogs treated with an anthelmintic was found re-infected 3 months later, it was impossible to calculate accurately the of infection over a 3-month period. Information about the feeding, sleeping and roaming practices of the dogs was also gathered using questionnaires and direct observations.