Twenty two multiparous and primiparous Holstein cows were utilized in a completely randomized design to determine the effects of feeding diets containing linseed or cotton seed as sources of n-3 or n-6 FAs on milk production, uterine health, immunity, reproductive responses of heat stressed cows during the transition period. Dietary treatments were initiated 20-35 d prior to estimate calving date and continued till confirmed pregnancy postpartum. Diets were formulated to be isocaloric and isonitrogenous and started feeding the pre calving diets at July for the pre calving cows and the post calving diets were fed tell conception. Dry matter intake (DMI) was measured and recorded, the average 1^st three months postpartum milk production were calculated. Total mixed ration (TMR) ration were collected monthly, and analyzed. Milk samples were collected for analysis and measuring betahydroxybuterate (BHB), lysozyme and nitric oxide concentration. The obtained results showed no difference in the average DMI between the two groups in pre calving stage (12.5 for G1; 12.4 for G2, Kg/h/d), while, it was higher in the G1 (20.55) than in G2 (18.45) in the 1st three month post calving. Milk production was increased in G1 (36.42 ±0.14 kg) than in G2 (34.57± 0.20 kg) but they are not significantly different, Also there was no significant difference between the two groups in milk analysis for protein, fat, SNF, and lactose at W2, W4 and at W7 postpartum. BHB concentration at W2 PP was significantly lower in G1 (25±9.45 µ g/mol.) than those in G2 (81.25 ±9.15 µ g/mol.), lysozyme at w2, w4 and w7 PP was significantly decreased in G1 (94.10 ±30.73, 45.56 ±9.86, 26.15 ±11.12 µg/ml) than those in G2 (246.34 ±6.11, 217.21 ±9.56, 192.68±11.048 µg/ml) respectively. Nitric oxide concentration was significantly decreased in G1 (47.38 ±18.21, 18.43 ±3.45, 14.27 ±2.72 µm/ml) than those in G2 (91.79±9.55, 64.73 ±7.40, 42.53±6.31 µm/ml) at W2, W4 and W7, respectively. Uterine cytology (neutrophil concentration) at day 40 ± 3 PP was higher in G2 than G1 but they were not significantly different. Days to 1^st estrus and days to 1^st insemination were significantly lower in group one (36.92 ±0.52, 75.0793±0.68) than those in G2 (86.18±0.64, 88.94±0.53) respectively. Days open and I.N. in G1 (172.89±3.13, 3.19±0.06) were lower than those in G2 (195.42±2.78, 4.07±0.07) but they were not significantly different. Conception rate (CR %) at 1^st, 2^nd and 3^rd insemination was higher in G1 (10%, 50%, 20%) than those in G2 (8.33%, 25%, 8.33%) and also repeat breeder (%) was much greater in G2 (58.33%) than in G1 (30%). This study concluded that, usin gomega-3 FA may enhance the reproductive performance of dairy cows during summer season because of its anti-inflammatory potency, leading to a higher chance of survival of the embryo when supplemented during the periconceptual period by reducing the oxidative stress.