The effect is considered of current injection on photoconduction. A theory is described which suggests that the effect of current injection on photoconduction will be most important for thin film low conductivity photoconductors, at high electric fields and in which surface exciton dissociation occurs. An equation is derived which enables the prediction of the time, voltage, and intensity dependence of photoconduction. These predictions are compared with the characteristics of the organic photoconductor μ‐chloro‐phthalocyaninato‐aluminium, which are measured using a chopped light technique.