The in vitro rumen fermentation parameters and the antimethanogenic potential of three Asteraceae species: Chamaemelum nobile, Centaurea pulata and Chrysanthemum segetum were determined. Serum bottles containing 200 mg of each plant and 30 ml of the culture medium (artificial saliva plus rumen juice) were incubated for 24 h. After incubation, pH, volatile fatty acid (VFA), ammonia (NH3) and methane (CH4) productions were recorded. Methanogens and protozoa were quantified using a Real Time PCR technique (qPCR). Cumulative gas productions, in vitro organic matter digestibility and VFA were not significantly affected by the added species when compared to the control (P > 0.05). The effects of Chamaemelum nobile and Chrysanthemum segetum on methane production, NH3 and acetate to propionate ratio (C2:C3) were similar. The two species were able to modulate rumen fermentation to produce significantly lower CH4 concentrations (-24.3% and -27.1%, respectively) compared to the control. C.pulata produced the highest cumulative gas and stimulated the microbial metabolism with an increase in C2:C3 ratio, NH3 and methane production (P 0.05). No significant effect of the three species on methanogenic Archaea and protozoa was registered (P > 0.05). The three species studied herein show a good potential for mitigating ruminal methane production without any undesirable effects on the main fermentation parameters.