In summer 2008, two fatal cases were observed in Northeastern Greece: a Crimean-Congo hemorrhagic fever (CCHF) case (first report in Greece) and a Mediterranean spotted fever case. In total, 537 ticks removed from humans who referred for this reason to the two hospitals of the region during June-September 2008 were identified. The vast majority of them (81.5%) were Rhipicephalus sanguineus, which is the main vector of Rickettsia conorii, while Hyalomma marginatum, the main vector of CCHF virus, accounted for 5.2%. The increased aggressiveness of R. sanguineus might be related to the weather conditions occurred during 2007-2008, while a variety of factors, including climate, might play a role in CCHF emergence.