Scanning electron microscopy was used to describe pollen-stigma interactions during compatible and incompatible pollinations of hazelnut (Corylus avellana L.), a species possessing sporophytic self-incompatibility. The stigmatic surface is of the dry type and was covered with elongated, rounded papillae. Compatible and incompatible pollen hydrated within 2 hours of pollination. Compatible pollen tubes emerged by 4 hours and grew into the style by 12 hours after pollination. Penetration of stigmatic papillae appeared to be intracellular in some cases. In incompatible pollinations, however, pollen tube emergence was delayed until at least 8 hours. The pollen tubes were distorted and did not penetrate the stigma.