Pathological examination of five adult chamois (Rupicapra r. rupicapra) found dead in two different regions from the Swiss Alps revealed pale mucous membranes and musculature, swollen spleen and haemoglobinuria. Histologically, haemosiderosis in the spleen and centrilobular hepatic necrosis were the predominant findings. On blood smears, small (approximately 0.84-1.47 microm), round to pyriform, peripherally located inclusions were present in the erythrocytes. PCR followed by sequencing of DNA extracted from blood or spleen of the infected animals revealed 99-100% identity of the amplified part of the 18S rRNA gene with GenBank entries attributed to Babesia divergens/Babesia capreoli. This is the first report of fatal Babesia infections in chamois raising the question of an emerging disease in this species.