The aim of this work was to study general morphological characteristics of pollen grains of Corylus avellana L. Seven samples of pollen were investigated. Samples were collected from different habitats in Ukraine – from botanical gardens (Kyiv, Kamianets-Podilskyi) and natural habitats (Kyiv region, Kamianets-Podilskyi, and Sumy region). We studied such morphological traits of pollen grains as length of polar and equatorial axes, diameter of pores, and shape of the pollen grain (elongation index). Analysis of morphological characters of pollen was carried out using electron microscope. Comparison of data was performed with the data of the base polleninfo.org. During research the differences in these parameters were marked. Pollen grains of C. avellana are generally isopolar, from suboblate to oblate or oblate-spheroidal, and contain 3 pores. The article contains an attempt to explain the size variations noted for the pollen collected from different habitats.