This study aimed to evaluate the effects of tannin extract and n-3 fatty acid supplementation on nutrient digestibility, ruminal parameters, blood metabolites, and enzyme activity in lactating ewes. Thirty-six lactating ewes were allocated to 6 experimental groups. The dietary treatments were as follows: 1) control, 2) diet supplemented with 2% dry matter (DM) oak leaf tannin extract, 3) diet supplemented with 2% DM grape pomace tannin extract, 4) diet supplemented with 2% DM linseed oil, 5) diet supplemented with 2% DM oak leaf tannin extract and 2% DM linseed oil, and 6) diet supplemented with 2% DM grape pomace tannin extract and 2% DM linseed oil. The results showed the significant effects of treatments on final body weight, digestibility, and some blood metabolites (P < 0.05). Therefore, the treatment groups had higher final body weight, better nutrient digestibility, and higher values of blood parameters. In conclusion, our results showed that the dietary tannin extract and the n-3 fatty acid source improved nutrient digestibility and blood metabolites, and they had a trend of improving the ruminal volatile fatty acid profile while not having any adverse effects on the animals' performance.