The objective of this study was to investigate the effects of increasing doses of 3 aromatic plants Carum sp. (CAR), Coriandrum sp. (COR) and Satureja sp. (SAT) as a natural dietary additive on ruminal metabolism in Sarda dairy sheep. Forty-four Sarda dairy ewes (BW = 45.11 ± 4.62 kg) were randomly divided into 4 groups (11 ewes per group) assigned to an aromatic plant or to the control (CON). The 3 plants were tested, for each group in chronological order, at 3 increasing doses (low = 25g, medium = 75g and high = 125g), each supplied individually for 21 d during the 2 daily machine milkings. The ewes also received during the day dehydrated alfalfa, beet pulp, corn and pea meals. Rumen samples were taken by using a stomach tube. Rumen pH (mean value 6.87) was influenced by type of aromatic plant and dose level (P < 0.004), but not by their interaction. The ammonia content was higher in CON and COR groups (18.20 and 19.45 mg/dL, respectively) compared with CAR and SAT (14.79 and 15.87 mg/dL, respectively), and it was influenced by plant (P < 0.001) but not by dose or their interaction. The molar proportions of acetate and propionate were affected by diet and dose level (P < 0.05), with the higher values in CON and SAT (41.8% and 11.0%; 38.1% and 10.3%, respectively), while their ratio was influenced only by the dose level (increased from 3.19 to 4.34 for the low and high dose respectively). The molar proportion of butyrate was affected only by the type of plant, with the lowest value in COR and CAR (7.86% and 7.80%, respectively). A strong interaction (P < 0.001) between type of aromatic plants and dose level was detected in the concentration of odd-branched-chain (OBCFA), saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids. In particular, CON and SAT groups had the higher concentration of OBCFA (7.93 and 7.86 g/100g FA, respectively) and PUFA (5.04 and 4.42 g/100g FA), while the concentration of SFA and MUFA were higher in CAR and COR groups. These results suggest that the aromatic plants used altered the FA profile of the rumen.