The paper tests for a link between the level of unionization and net investment rates in Canadian manufacturing. Evidence from a balanced panel of 18 industries between 1967 and 1987 reveals a negative non-linear relationship. The negative relation occurs at levels of unionization between 0 and approximately 50%, with a plateau above this level. At the mean level of unionization, a one percent increase in the unionization rate leads to a 0.7 percent drop in the net investment rate. Net investment rates do not appear to respond to measures of strike intensity.