Inequality of agricultural labour productivity across the developing world has increased substantially over the past 40 years. This article asks: to what extent did the diffusion of Green Revolution seed varieties contribute to increasing agricultural labour productivity disparity across the developing countries? We find that 22 per cent of cross-country variation in agricultural labour productivity can be attributed to the diffusion of high-yielding seed varieties across countries, and that the impact of such diffusion differed significantly across regions. We discuss the implications of these findings for policy directed at increasing agricultural labour productivity in the developing world.