An, H. and Carew, R. 2015. Effect of climate change and use of improved varieties on barley and canola yield in Manitoba. Can. J. Plant Sci. 95: 127-139. A stochastic production function was estimated to investigate the effect of fertilizer inputs, changes in weather conditions and the use of improved varieties on barley and canola yields and its variability in Manitoba. Adoption of improved barley varieties did not have a significant effect on yield, while the adoption of herbicide-tolerant hybrid canola varieties was positively correlated with yield. An increasingly warmer climate in Manitoba is expected to have a slightly negative effect on mean barley yield and yield variance. In contrast, a warmer climate is expected to have a negligible effect on mean canola yield, but a positive effect on yield variability. Our results showed that a projected 50% increase in growing degree days would lead to a decrease of less than 1% in barley and canola yields.