The paper presents the course of the grass (Poaceae) pollen season in Bialystok, Bydgoszcz, Cracow, Sosnowiec, Lublin, Olsztyn, Szczecin, Drawsko Pomorskie, Warsaw, Piotrkow Trybunalski, Opole, Wroclaw and Zielona Gora in 2018. The pollen of grass is the primary trigger of pollen allergies during the summer months. It causes some of the most severe and difficult-to-treat symptoms. Measurements were performed by the volumetric method (Burkard and Lanzoni pollen samplers). The pollen season of Poaceae started first in Sosnowiec, Lublin and Opole in the third decade of April. The highest, record airborne concentration of 243 pollen grains/m3 was noted in Lublin on June 19th. The maximum values of seasonal pollen count occurred between of May 27th and June 4th in all cities. The highest grass pollen allergen hazard occurred in 2018 in Warsaw, Lublin and Zielona Gora.