Two strategies to improve the efficacy of the shell-vial method for Rickettsia were analyzed. Blood samples from 59 patients with Mediterranean spotted fever (MSF) were examined using the shell-vial technique. (i) DNA from positive lenses was obtained when they were contaminated. (ii) Blood sample from one patient was cultured in 17 shell-vials. R. conorii was identified in four cases by polymerase chain reaction (PCR)-RFLP. Three of these were obtained from cells adherent to lenses and the fourth one by using total patient blood sample. Rickettsia isolation using all blood samples as well as DNA from shell-vial lenses could be useful in the study of rickettsial infections.