The aim of this work was, after a coccidiosis outbreak in a farm rearing red-legged partridges (Alectoris rufa) in Brittany (France), to identify the Eimeria species and describe gross lesions induced by three of them (E. kofoidi, E. caucasica and E. legionensis) after experimental infection. E. kofoidi oocysts measured 19.3 x 16.3 µm on average; neither micropyle nor oocyst residuum were present, but one, two or more small polar granules were visible. After inoculation of 300,000 oocysts per partridge, severe gross lesions were observed in duodenum and jejunum, characterised by thickened oedematous mucosa and lumen filled with thick mucous, gas and sometimes false-membrane due to sloughed epithelium. E. caucasica oocysts were on average 29.8 x 19.5 µm in size; no oocyst residuum was observed, but a large granule was well visible. E. caucasica also invaded both duodenum and jejunum, causing hemorrhagic points on the serosal surface, as well as mucoid duodenitis and catarrhal enteritis when 30,000 oocysts were inoculated per bird. E. legionensis oocysts measured 22.6 x 14.9 µm on average; they presented a clear micropyle beneath which one or two granulations were present. E. legionensis mainly invaded the caeca; low mortality was observed at the dosage of 200,000 oocysts per bird. Caecal walls were thickened and caseous material was condensed into off-white cheesy cores. For each species, oocyst shedding started 5 days post inoculation (DPI), peaked at 9, 8 and 6 DPI for E. kofoidi, E. caucasica and E. legionensis, respectively, then decreased and persisted until 15 DPI (end of examinations).