Adherence to therapies is a primary determinant of treatment success. Poor adherence attenuates optimum clinical benefits and therefore reduces the overall effectiveness of health systems. Medicines will not be effective if patients do not follow prescribed treatment. Adherence to longterm therapy for chronic illnesses in developed countries averages 50%. In developing countries, the rates are even lower. The ability of patients to follow treatment plans in an optimal manner is frequently compromised by more than one barrier, usually related to different aspects of the problem. These include: the social and economic factors, the health care team/system, the characteristics of the disease, disease therapies and patient-related factors. The instrument that was used consisted of two parts: part one collects socio-demographic data, part two is the eight-item original Morisky scale. The study included 250 hospitalized patients aged 19-92 years. Information on adherence to therapy was retrieved mainly from the patients medica! records. The average age of the patient was found to be 65 years, and each patient bas an average 5 comorbidities. Comorbidities, side effects, lack of knowledge and rehospitalization are factors that influencing adherence. Approximately half of patients (3 7%) bave low adherence. This study bas shown that patients on long-term therapy for chronic diseases have poor adherence. Health professionals need to be trained in adherence and it is necessary that the patient, the family and the community who support him or her all play an active role.