The cowslip growing in grassland areas and forest edges is widely recognized as a threatened species due to the continuous extinction of these valuable habitats. It is a perennial, herbaceous plant with green elongated leaves up to 20 cm long, multiple stems, and flowers with orange dots, blooming in clusters of 5-16. The cowslip is heterostylous, occurring as S-morph (short female reproductive organ and longer male reproductive organs visible from above) and L-morph (visible long female and shorter male reproductive organ). The aim of the study conducted in May 2022 was to determine the state of cowslip populations and frequency of S- and L-morph at the three study sites - Mrkopalj, Matić Poljana, and Begovo Razdolje in the Mrkopalj municipality. The municipality of Mrkopalj is located in the southeastern part of Gorski kotar (Croatia). The area is covered with fertile arable land (today mostly uncultivated), as well as with forests, pastures, and meadows rich in biodiversity. In recent years, the natural overgrowing of arable lands and grasslands in this area has become more pronounced and expressed in the loss of species and landscape diversity. The cowslip populations were found in meadows, usually mown for hay. A total of 350 cowslips were counted. The frequencies of the S- and L- morph (S / L) at the studied sites were 59.09% / 40.90%, 59.66% / 40.33% and 42.97% / 57.02%, respectively. The results indicated variations in the development and frequency of S- and L-morphs at studied sites, which may lead to the population decline.