The proper greenhouse climate depends mainly on ventilation. A lot of experimental work is done describing the ventilation in a mathematical model based on greenhouse geometry and surrounding conditions. Some computational fluid dynamics (CFD) studies are done in this field but they were all two-dimensional. In this presentation, a three-dimensional CFD study on the wind driven ventilation of a Venlo-type greenhouse is given. The calculations are verified by experimental results from tracer gas measurements. From the study it is concluded that the ventilation has a strong three-dimensional character due to the wind direction and the geometry of the greenhouse. The microclimate, hence the temperature distribution in the greenhouse subscribes this as well.