Summary This study was carried out in El-zahraa arab Horse Stud, Cairo, Egypt. 125 Arabian mares were included, 100 of them were prospectively investigated from Stud Book for studying gestation length and Season of parturition of mare. The later 25 mares:colts were were used for recording gestation period and behavioural activities. The results obtained revealed that: (1) Gestation length and Season of parturition of mare: - Average gestation period in Arabian mares was 327.71+1.21 days. Colt were carried 4.58 days longer than fillies (330.01+1.23 days for Colt and 325.42+1.16 dats for fillies ). - There was no sign1f icant effect of strain of the mare on the duration of pregnancy, gestation length in Saklawi mares was 327.46+l.07 days, while in Kohelan, Hadban, Dahman and Obeyan Was 326.56+1.16, 327.33+1.19, 328.00 +2.30 and 329.2+2.21 days; respectively. There was no Significant effect of mares age on the length of gestation length in 5 years old mares was 327.75+-0.87 , in 6-12 years 0ld mares was 328.5+0.62 and in over yeas old mares was 326.89+1.24. The effect of Season of Conception on the length of gestation was not Significant, whereas the gestation period resulting from conseption in spring, Summer, autumn and Winter Was 330.81+l..39, 327 .59+2.0, 323.25+2.15 and 329.09+2.16 days, percentage foaling was occurred in spring (39.78), while in winter , autumn and summer was 29.25% , 17.42% and 13.54%, respectively. (2) Changes in body temperature of pregnant mares two week pre-partum The mean body temperature of pregnant mares during 13days pre-partum was 37.93°C, while the mean body tempeIature at day one pre partum was 37.83°C. The difference was 0.1°c At (day 0), the mean body temperature was 37.97°C difference between day one prepartum and day 0 was 0.14c. Al so it was noticed that 60% of mares showed drop in their body temperature at day one pre-partum (0.13 C), 20% of observed mares unchanged and 20% showed rise in their body temperature (0.12°c). (3) Behaviour of pregnant and lactating mares two weeks before and after parturition : The time spent (hours) eating by pregnant mares during day, night and 24 h was 6.44 h, 3.02 h and 9.46 h; respectively, while standing time was 4.66 h, 6.5 h and l1.16 hours, walking time was 0.23 h. 0.15 h and 0.38 hour and lying time during night was 1.8 hours. In lactating mares, the time spent eating (hours) during day, night and 24 h was 7.25 h, 4.82 h and 12.07 h. While the standing tlne 3.88 h, 4.86 h and 8.74 hours; respective ly. Walking time ( hours) during day, night and 24 h was 0.21 h, 0.13 h and 0.34 h and the lying time (hours) was 1.62 during the night. The changes in behavior after parturition may indicate that nutritional demands of lactation and maternal protective behaviour towards their foals. (4) Parturien t behaviour : The most common behaviour traits which occurred during pre-parturient stage was waxing (8-22 h before birth ) frequent urination & defaecation, pawing the ground and Looking at the flank. Most mares gave birth at night (40% of observed cases gave birth between 6-10 p.m, 50% between 10-2 a.m and 10% between 2-6 a.m). - It was observed that by dam' s age advancing , the time required for parturition was decreased. The length of first stage (min.) Was 49.5+2.12, 38.66+8.06 and 36.25+4.59 min. in 5 years group, 6-11 years group and over 12 years group; respect ively. While the length of 2nd stage for the same animal groups was 23.5+2.07, 18.0+5.6 and 14.0+7.57 min. The length of 3rd stage was 41.0 +8.4, 39.5+5.6 min respectively. All mares gave birth in recumbent position. - The mean time (min.) for rupture of umblical cord was 9.2 min after parturition. -The total licking time increased by mare ageadvancing. , licking time (min.) was 31.5+8.5, 35.3+2.07 and 46.0+3.0 min. in 5 years group, 6-11 years group and over -12 years group , respectively. -the frequency of nurcing decreased by progress of the foal age , the frequency of nursing at first weak was 4 times each hour and then decreased gradually to reach 2.4|h during the 6th week. -the distance between mare and their foals was increased by the foal age. The percentage time the mares and their foals spent in distance less than 1m during 1st week was 86.42+-6.28% while during the 6th week was 54.16+-6.62% but at a distance more than 5m in the 1st week was 3.41% and 24.6% during the 6th week of life. -coprophagia was observed , the mean age when it was 1st seen at 8.2 days of foals life(9.6 days in male and 6 days in female), while the number of coprophagia incident in males was 4.3 times and 7 times in females during the observation period 6 weeks. The mean length of coprophagia incident was 116.3 seconds. coprophagia may serve to introduce bacteria into the foals gut and supply several enzymes, vitamins and bile acids as it was suggested by many authors.