Abstract Little is known about Eimeria-induced coccidiosis in partridges. After a coccidiosis outbreak in a farm rearing red-legged partridges (Alectoris rufa) in Brittany (France), three Eimeria species were identified as Eimeria kofoidi, Eimeria caucasica and Eimeria legionensis. This study aimed to reproduce the effects of the disease occurring in field conditions, in the absence of preventive treatments, to further build a coccidiosis model, helpful for coccidiostatic development. The pathogenic effects of a single infection with Eimeria kofoidi, E. caucasica and E. legionensis were evaluated, as well as the effects of multiple infections associating two or three of these species in red-legged partridges. Thirty-one-day-old birds were individually inoculated with Eimeria spp. and clinically followed up until 49 days of age. Mortality, lesion scores, daily oocyst production and growth were used as assessment criteria. Single infections with 250,000 E. kofoidi, 30,000 E. caucasica or 100,000 E. legionensis oocysts did not increase mortality rate compared to uninfected birds, whereas the combination of 3 species caused significant 28% mortality (P<0.05). Five days post inoculation, lesions scores in the proximal intestine (duodenum/jejunum) decreased in dual-infected birds and tended to decrease in triple-infected birds compared to lesions in mono-infected birds. The highest caecal lesion score was recorded in birds co-infected with E. kofoidi and E. legionensis. In multi-infected birds, the total number of oocysts excreted per gram of faeces was lower than the sum of oocysts excreted by mono-infected birds. Each single infection caused significant growth depression and even weight loss in E. legionensis infected birds (P<0.05). Dual or triple infections worsened this effect. Eighteen days post inoculation, only mono-infected birds had recovered. Their weight gains were not different from that of uninfected birds, whereas growth was significantly depressed in dual-infected birds, notably in co-infected E. kofoidi and E. legionensis birds and worsened in triple-infected birds (−34% and −78% growth depression, respectively). Our results indicate that the oocyst doses used were suitable in single infections or should be slightly reduced for future studies requiring significant growth retardation (about 25%). In mixed-infections, the effects on growth are considerably increased; therefore, oocyst doses must be reduced, approximately 125,000 E. kofoidi+15,000 E. caucasica+50,000 E. legionensis oocysts can be recommended. The study model presented here is valuable to conduct further research such as for assessing the ability of these birds to mount immune response against Eimeria spp. or for selecting efficient molecules to struggle coccidiosis of red-legged partridges.