The diagnosis of multiple sclerosis (MS) is a life-altering experience that has far-reaching and diverse implications for newly diagnosed patients and their families. Since the disease is complex and highly variable, it places physical, emotional and social challenges on everyone concerned. A number of responsible decisions must be made, the most difficult one being the consent to long-term therapy. Joint effort of both physicians and patients allow the latter to take up properly new life circumstances, get adequate motivation, right and regular implementation of the long-term treatment plan aiming to prevent the disease progression. The management of many chronic diseases involves medications that must be injected on the frequent basis. In MS, such injections can reduce the frequency of relapses and slow the disease progression. Pretreatment injection self-efficacy expectations, injection anxiety, therapeutic expectations and ability to self-inject are significantly related to adherence. Poor patient adherence to long-term therapy severely compromises the treatment effectiveness.