Biokovo and Dinara Nature Parks belong to the Dinarides mountain range. They stand out for their karst geomorphological values and biodiversity. Both areas are influenced by similar ecological factors, although part of the Dinara Nature Park includes three karst fields and the upper course of the river Cetina. The paper compares the biological value of two parks in the composition of plant and animal communities and the endangerment of wildlife. The Sørensen similarity index compared amphibians, reptiles, nesting birds, and mammals. In vascular flora and invertebrates, their endemics were compared. In addition, a survey was conducted on 180 respondents whose goal was to explore knowledge of the biological values of the Biokovo and Dinara Nature Parks and to get acquainted with the public's views on nature and environmental protection. The Sørens index showed similarities in the composition of amphibians, reptiles, nesting birds, and mammals of the two parks. Both parks have a similar number of species from the group of amphibians, reptiles and mammals while the bird class is much richer on the Dinara. The similarity was also shown in the number of plant endemics, while the endemicity of invertebrates of the Biokovo Nature Park is more diverse. The results of the survey showed satisfactory knowledge about the essential features of the two nature parks and the great untapped potential in volunteering for nature and environmental protection.