Objectives: The aim of the study was the epidemiological analysis and evaluation of selected clinical and sociodemographic factors in Polish patients with primary progressive multiple sclerosis. Methods: The study included patients from 7 provinces in central and eastern Poland registered in the Registry of Patients with Multiple Sclerosis on 31 December 2016. The incidence of various forms of the disease was compared, and clinical, demographic and social disparities between relapsing-remitting and primary progressive multiple sclerosis were analysed. Results: Of 3,199 registered patients, 2,188 persons (66.2%) had the relapsing-remitting form of multiple sclerosis, 774 (24.2%) had the secondary progressive type and 307 (9.6%) suffered from primary progressive disease. The first symptoms of primary progressive multiple sclerosis appeared almost 10 years later than in patients with the relapsing-remitting type (39.2 ± 11.4 vs. 29.8 ± 9.8). The period from the first symptoms to diagnosis was more than twice as long in patients with primary progressive multiple sclerosis (5.8 ± 3.4) as in those with relapsing-remitting disease (2.4 ± 1.6). The average degree of disability in the Expanded Disability Status Scale was similar and amounted to 3.2 ± 2.1 for relapsing-remitting and 3.6 ± 2.4 for primary progressive multiple sclerosis. The relapsing-remitting form was observed more often in women (2.4:1), and the primary progressive form appeared with equal frequency in both sexes (1:1). Disease-modifying treatment was received by 34% of patients with relapsing-remitting and in only 1.9% of patients with primary progressive multiple sclerosis. Conclusions: The primary progressive form affects approximately 10% of Polish patients with multiple sclerosis. The first symptoms appear at about 40 years of age with equal frequency in both sexes, and its diagnosis takes more than twice as much time as in the case of relapsing-remitting multiple sclerosis.