We conducted a questionnaire-based case-control study to identify risk factors for cystic echinococcosis (CE) in Lima, Peru during July-December 2005. Data were obtained from 32 cases and 64 controls. Multivariate conditional logistic regression showed that having owned > or =10 dogs [adjusted odds ratio (AOR) 8.7, 95% CI 1.3-57.5) and raising sheep (AOR 5.9, 95% CI 1.2-28.1) were independently associated with CE. The belief that CE could be transmitted by food (AOR 0.1, 95% CI 0.01-0.7) and breeding goats (AOR 0.02, 95% CI 0.001-0.6) were protective factors against CE transmission. Our results suggest that preventive measures to decrease the transmission of echinococcosis to humans in Peru should include limiting the number of dogs owned and encouraging owners to restrict dogs' access to food and water used for human consumption.