The aim of this experiment was the comparison between feeding saturated granular and calcium salt forms of fatty acids in long term on performance, energy balance and reproduction of dairy cows. In this study, two groups of Holstein dairy cows were used in two separate pens. Cows within and between two pens were similar in milk yield (45.76 ± 6.2), days in milk (61.12 ± 13) and parity (mean = 1.86). Cows were randomly assigned to two experimental diets. 1) Basal diet + supplemental calcium salt of fatty acid (2 to 3% of DM of diet or 500 g per day for per head), 2) basal diet + Saturated fat (2 to 3% of DM of diet or 500 grams per day for per head). The experimental period was 90 days, which was divided into two-week periods and sampling carried out at the end of each period. There were no significant differences for production milk and energy corrected milk between two treatments, although the 3.5% FCM tended to be different (P = 0.09). The interaction observed between treatment and the level of production, that indicates the better effect of supplemental saturated fat than calcium-salt form in the high-producing dairy cows. The percentage of milk protein was significantly different between two groups ( P 0.05), so that the calcium-salt of fatty acid significantly increased the percentage of milk protein. The results showed that the increase in percentage of milk protein was different between low-and high-producing cows ( P = 0.05). Supplemental saturated fat significantly increased milk fat percentage ( P 0.05), although differences were not significant between low-and high-producing cows. Saturated fat increased milk fat production in comparison to calcium salt of fatty acid, although this effect did not follow in the different levels of production. The percentage of milk lactose was increased by saturated fat than calcium salts. Feed efficiency based on raw milk (kg)/ dry matter intake, 3.5% FCM corrected milk (kg)/ dry matter intake and energy corrected milk (kg)/ dry matter were significantly ( P 0.05), different between treatments. When cows were categorized based on the milk level, only the difference in 3.5% FCM corrected milk (kg)/dry matter intake was significant. This significant difference indicated an increase in feed efficiency by saturated fat supplementation. Supplemental calcium salt of fatty acid in comparison to saturated fat significantly increased dry matter digestibility ( P 0.05). Also organic matter digestibility ( P = 0.06) and neutral detergent fiber digestibility ( P = 0.10) tended to increase by supplementary calcium salt of fatty acid. Treatment containing saturated fat significantly ( P 0.05) increased blood urea nitrogen and decreased albumin concentration (P 0.05) than calcium salt of fatty acid. Alanin amino transferase tended to increase by saturated fat ( P = 0.08). In conclusion, feeding saturated granular fat increased 3.5% FCM yield, milk fat percentage lactose and feed efficiency, decreased milk protein percentage and reproductive parameters were not affected by treatment. Keywords : dairy cattle, palmitic acid, sulfur, calcium salt of fatty acids, fat, reproduction.