Objectives: The objective of this dissertation is to ascertain to what extent patients suffering from chronic diseases follow the advice given by their physician and whether they regularly get their supplies of the prescribed medicine. Materials and Methods The research was conducted in selected pharmacies of the ZU Farmacia. It used the epidemiological analytical method to investigate the dynamics of retrieving the medicine, based on the pharmacy register over a period of six months. On the basis of the pharmacy records, the dynamics of the retrieval and dispensing of the medicine for particular patients have been determined, together with the Medication Possession Ratio (MPR) that represents the ratio of drug availability for a particular treatment. Results: The research included 142 patients suffering from chronic diseases. Most of the patients (n=92; 64,8%) were using two (n=54; 38%) or three (n=38; 26,8%) medicines. The compliance of patients showed a steady decrease during the treatment, with only 46% of patients strictly adhering to the prescribed treatment after five medicine collections (five months). Conclusion: Decreased adherence with the prescribed treatment is an important issue in the long-term treatment of patients suffering from chronic diseases. Some of the consequences of poor adherence3 are: the advancement of the disease, declining health and the deterioration of the patient’s quality of life, all of which increase the overall cost of the health care system. Patients need to be informed about the importance of consistently following through with the prescribed treatment and in this regard, the multidisciplinary approach of all those involved in the health care system is essential. Pharmacists play a key role in the early detection of patients who comply poorly with the prescribed treatment and in further educating them and raising the level of patient awareness.