Morphology and ultrastructure of pollen grain were described for six cornelian cherry (Cornus mas L.) cultivars (Degirmendere, Erkenci Degirmendere, Iri Bardak, Yuvarlak Bardak, Uzun Memeli, and Bugur) using light microscopy and both scanning and transmission electron microscopy. Pollen grains of cornelian cherry cultivars are trizonocolporate, the germinal furrow extending almost the full length of the grain axis. Pollen grain length for the studied cultivars ranged from 23.63 to 25.13 mu m. Two different pollen shapes were observed: oblate spheroidal and prolate spheroidal. Significant changes in various layers of the pollen wall are as follows: the thickness of the intine: 233.1 to 406.4 nm, exine: 510.2 to 842.7 nm, and total wall 851.4 to 1175.8 nm. Percentages of abnormal pollen grains ranged from 3.9% to 27.6% among the cultivars. Abnormal pollen grains were categorized as: 1) shrunken pollen grains of abnormal appearance with little cytoplasm; 2) pollen grains of normal appearance with little or no cytoplasm; and 3) shrunken, abnormal pollen grains of elliptical shape with a colpate-type aperture.