Mediterranean spotted fever (MSF) is a tick-borne rickettsial disease. It is endemic in Portugal and Ricardo Jorge recognized it in 1930. Rhipicephalus sanguineus is the main vector and reservoir of the disease. In Portugal the etiologic agents are two strains of Rickettsia conorii complex: R. conorii Malish and "Israeli tick typhus". MSF is clinically characterized by a vasculitis process with the classical clinical triad of fever, rash, and lesion at the site of tick bite. Although the majority MSF cases are considered benign, last years some districts presented more severe cases than expected. The reported incidence of MSF in Portugal for 1989 to 2000 was 9.8/10(5) inhabitants, the highest incidence compared to other mediterranean countries. Alentejo was the region who presents the highest incidence with 31/10(5) inhabitants. Nevertheless, Bragança was the district which appears with greater number of cases, 62/10(5) inhabitants. The highest annual incidence rate reported was among children, peaking in those 1-4 years of age with 60.2/10(5) inhabitants. Observation of mortality rates have shown that Beja district have the highest mortality rates for MSF in Portugal, but in 1997 in this district, mortality have unexpected values with 7.6 deaths per 100,000 inhabitants have occurred. Although is an obligatory notifiable disease, high number of underreported cases are detected.