Medical University, Pharmaceutical Faculty, Sofia, Bulgaria DOI : 10.12991/201014452 Improving the safety of the patient is a significant challenge for the national health systems, as it is for many health services around the world. Community-acquired pneumonia (CAP) is a common, potentially life-threatening disease that is associated with much morbidity, mortality and use of healthcare resources. The aim of the study was to clarify and evaluate the frequency of antibiotics' prescribing for inpatients, hospitalized due to CAP, leading factors for prescriptions' changes during treatment and medical doctors' attitude to patient safety problem. We conducted a retrospective investigation of the medical records for 107 inpatients hospitalized due to CAP. The used methods were pseudo-randomization; experts' analysis and non-interventional pharmacoepidemiologycal evaluation of the variations frequencies. We also classify the factors for changes in medicines prescriptions in five main groups. Data shows that more than 33% of the patients with CAP have had one or more variations in drug therapy during hospital stay. Most common change in the therapy is adding another antibiotic (67%) due to lack of therapeutic effect (63%) or specifying diagnosis (26%). The leading factor for additional antibiotic prescribing is starting therapy without microbiological specification of the diagnosis. Regarding patient safety the interviewed medical doctors (MDs) declared problems about healthcare system financing, institutional limitations, diagnostics, lack of clear rules and standards for practice. Efforts to improve the use of antibiotics for inpatients with CAP should consider the range of barriers that care providers face in everyday practice. Keywords : Patient safety, community-acquired pneumonia, antibiotics, medical doctors' attitude