We derive a simple expression for the escape flux which takes into account horizontal winds at the exobase. The escape flux is shown to increase with the wind velocity and becomes much larger than the Jeans escape flux for velocities approaching the thermal velocity. This model is applied to terrestrial 4He, where we determine the conditions required for wind-enhanced escape to contribute to the overall 4He budget. For completeness, we also derive an expression for the escape flux when only a vertical wind is present at the exobase.