The objective of this study is to characterize purebred Arab mares' milk through monitoring its physicochemical and microbiological composition during different lactation stages and to test its ability to coagulate. Sixteen purebred Arabian mares were selected among 45 mares with approximately the same foaling dates. Milk samples were collected once a week for each mare during 4 months of lactation and analysed in three replicates for physicochemical composition, nitrogen fractions, somatic cell count and total bacterial count. Coagulation assays were carried out in triplicates on fresh mare's milk using increasing doses of calf rennet, starter (Streptococcus thermophilus) and CaCl 2 . Arab mare's milk is characterized by an alkaline pH, low-fat and protein contents and high lactose content. The somatic cell and bacterial counts are very low, indicating good health status of mares. Fat and protein contents decreased as the stage of lactation progressed. However, as lactation number increased, fat level tended to increase while protein level tended to decrease. Clotting assays proved that it is possible to coagulate Arabian mare's milk using appropriate doses of calf rennet and starter, while respecting the coagulation procedures and parameters.