To determine whether the incidence of canine leishmaniasis has increased on Crete, Greece, we fitted infection models to serodiagnostic records of 8,848 dog samples for 1990-2006. Models predicted that seroprevalence has increased 2.4% (95% confidence interval 1.61%-3.51%) per year and that incidence has increased 2.2- to 3.8-fold over this 17-year period.