Multiple sclerosis is a chronic autoimmune demyelinating disease of the central nervous system. Prevalence of the disease is rising, and although its etiology is still unknown, genetics, person's immunological characteristics and environmental factors are thought to have major role in disease formation. Epstein-Barr virus infection, smoking and vitamin D deficiency are some of the risk factors especially important in etiology of MS. Patients can, depending on localization of lesions, present with various symptoms. In most of them disease starts with clinically isolated syndrome. 85% of patients have relapse remitting multiple sclerosis and majority of them, if left untreated, will over the years transition to a secondary progressive disease course. Smaller number of patients have primary progressive multiple sclerosis characterised by progression from the disease onset, without initial relapse remitting phase. The mean age of onset in PPMS is around 40 years old and prevalence is approximately equal in both genders. Among cortical demyelination and lower intensity of inflammation, PPMS is characterised by a global inflammatory process and diffuse axonal injury in normal appearing white matter. The majority of the patients present with progressive spastic paraparesis. Ataxia and the other cerebellar and brainstem symptoms are also very frequent. Diagnosis of PPMS is based on McDonald criteria which were revised in 2017. Positive paraclinical criteria and one year of disease progression are needed to diagnose this type of MS. Diagnosis is made retrospectively and it can often be very challenging with wide range of differential diagnosis that need to be excluded. Besides ocrelizumab, the only drug approved for PPMS, symptomatic therapy is base for treatment of these patients.