Bromus inermis Leyss (smooth brome) is an invasive perennial grass in Fescue Prairie in North America. Prescribed burning is a potential method of controlling this exotic, but its responses to burning in this grassland are not known. This study was conducted to determine the impacts of a single burn in the autumn or spring on the growth and water relations of B. inermis in Fescue Prairie in central Saskatchewan. In 1 yr, leaf xylem water potential and stomatal conductance were lower in plants burned in the autumn than the reference and the spring burn. In another year they were generally similar among the burns and reference. Regardless of water stress following burning, tiller densities, standing crop and the leaf area indices of B. inermis were not significantly different among the reference, autumn and spring burns. Because B. inermis is apparently resistant to fire effects and native species are suppressed by burning, fire may increase B. inermis in Fescue Prairie. Unlike grasslands dominated by C4 species, a single burn in autumn or spring while plants are dormant is not expected to reduce B. inermis in the C3-dominated Fescue Prairie. © American Midland Naturalist. Abstract reproduced by permission.