The rising plate meter (RPM) is a tool used for pasture biomass (PB) estimation. The goal of this study was to determine if the RPM can be used to estimate pasture biomass in complex mixed-species perennial pastures of Ontario, and to establish an equation for this purpose. Data from eight site-years in Ontario pastures was collected to establish a regression equation between pasture biomass and compressed sward height (CSH) as measured by the RPM. The calibration across all sites was PB=165*CSH. Additionally, influence of single species was tested in a separate plot experiment. The results of the species plot analysis demonstrate that different species may influence the recommended calibration. Finally, the plots were used to determine the influence of species and residual cutting height (5 or 10 cm) on annual pasture yield. These results conveyed that species do influence annual pasture yield, but residual cutting height had no effect.