ABSTRACT This study investigated the effects of the addition of Lactobacillus reuteri E81 (LRE) into rations of chukar partridges (Alectoris chukar) fed under heat stress (HS) conditions on fattening performance and meat quality. This study included 256 chukar partridges aged 1 day. The study comprised an adaptation period of 7 days and a fattening period of 35 days and included 8 different groups with 32 animals in each group. Each group was further divided into four subgroups with eight animals in each subgroup. At the end of the study, the best results in terms of fattening performance in the non-HS groups were obtained in the LRE 600 ppm group and in the HS groups, SLRE 200 ppm had the best effect on average live weight and average live weight increase, whereas SLRE 400 ppm had the best effect on FCR (p<0.05). The analysis of the samples collected from chukar partridges on day 21 showed that, there was no effect on the colour parameters and Thiobarbituric acid reactive substances (TBARS) level in the LRE in the HS and non- HS groups, whereas the meat pH level decreased in the SLRE 400 ppm group (p<0.05). The analysis of the samples collected on day 42 showed that there was no effect on colour parameters in the HS and non-HS groups. TBARS level decreased at the dose of LRE 200 ppm in the non-HS group, and the meat pH level decreased in both HS and non-HS groups (p<0.05).