Adherence to the prescribed therapy is a factor that significantly affects the outcome of the therapy, ie the health of the patient. In developed countries only about 50% of patients are adherent to long-term therapy. Poor adherence is a widespread problem that significantly compromises the success of therapy and results in worsening of disease, death and increased health costs. Patients` perceptions of medicines, their beliefs and attitudes about the necessity of therapy and concerns about unwanted effects are an important adherence factor as they affect patient's motivation to follow therapy instructions. Primary research was conducted in this paper, on the influence of patients`s perceptions of medicines on adherence. The study was conducted to investigate patients` perceptions of medicines, their necessity beliefs and concerns about potential adverse effects, with a special emphasis on determining patients` views about herbal remedies and their preferences in using herbal remedies, to determine patients` attitudes about physicians and the role of pharmacists, to investigate patients` adherence and determine connection between perceptions of medicines and adherence. The research showed that patients perceive medicines as necessary but are concerned about their unwanted effects. On the other side, herbal remedies are perceived as natural and safe and patients often use them without consultation with a physician/pharmacist. One third of patients stops taking prescribed medicines when symptoms disappear and 66% if they notice side effects. Improving adherence is an intervention that requires cooperation of all healthcare professionals and it is a key component for improving therapy outcomes. Pharmacists play an important role in creating and conducting these interventions as they are most accesible healthcare professionals and have the largest corpus of knowledge about medicines.