Multiple sclerosis (MS) is a neuroinflammatory, potentially disabling demyelinating disease of the central nervous system (CNS), with neurodegeneration being the most prominent in progressive phenotypes. The disease results in motor, sensory and cognitive symptoms, all of which can occur independently of one another. Patients with multiple neurological signs or CNS lesions that are separated in time are diagnosed with relapsing-remitting (RR) or primary progressive multiple sclerosis (PPMS). A progressive course refers to worsening of the neurological disability, independent of relapses. Cognitive impairment (CI) is a common but still challenging expression of MS and a frequent cause of socioeconomic decline and disability for MS patients. There is still no data regarding the direct relationship between cognitive impairment and the clinical course of the disease. Thus, cognitive deficits which occur during the early stages of the disease are the ones that need to be specially identified and addressed, to prevent worsening of CI, implicating a poor prognosis in MS. The Symbol Digit Modalities Test (SDMT) test is a valuable screening tool for CI and can be the starting point when assessing CI in MS patients when other comprehensive screening tools are not available. The neuropsychological assessment should also discriminate between CI and other causes of perceived deficits, including quality of life (QoL), depression, and anxiety. A healthy diet, no addiction lifestyle, regular physical exercise and the proper control of co-morbidities can positively affect cognition in patients with MS. Recent data also indicate that proper disease-modifying therapy (DMT) implemented early in the course of RRMS can stabilize or even improve cognition. Since there is no standardized protocol for identification and assessment of CI, further studies are needed in order to elaborate a "golden standard” for screening and diagnosing of cognitive deficits in MS, and for the development of evidence-based effective preventive methods and treatment approaches.