A herd of 44 Arab mares were observed in a 2500m² paddock in summer in Tunisia. Fifteen-minute focal animal samples and scan sampling were used to determine the time budget of the mares during the period from 9am to 3pm and study their social behaviour. A total of 42 hours of observation were performed. Chi square test and spearman correlation were used to analyse data. Locomotion was the most frequent activity with 27, 9 ± 19, 47%. Feeding and stand-resting were the following activities. The mares spent 14, 88 ± 18, 83% of their time alert-standing, 1, 03 ± 3, 51% self-grooming, 4, 75 ± 7, 19% drinking and 0, 83% ± 2, 64% interacting socially. Rolling was observed only once and mares were never been observed allogrooming, lying down, urinating, defecating nor vocalizing. Social behaviour was restricted to agonistic interactions and preferential associations that could be determined were very rare. The data obtained reveals restricted behavioural repertoires, unusual time budgets with a high frequency of active walk that constitutes the most frequent activity and a low level of social interactions. By modifying some management practices, we have tested, in a second part, the effect of some environmental factors on mares’ time budgets and social behaviour. These results are discussed in relation to other similar studies on domestic horses and questions of welfare assessment.