In the present study we analysed registered adverse drug reactions caused by 19 most used drugs in Bulgaria during three-year period. The cases were assembled from the spontaneous reporting system operated in our country. We described demographic characteristics of the patients, clinical diagnosis and reporting rates per 100 000 inhabitants for each drug. The data for antibiotics were compared with the results of our previous research. We analysed 188 adverse drug reactions i.e. 21 % of all reports received in the Centre for Drug Safety of the National Drug Institute. Adverse drug reactions type B such as oedema, allergy, coma, etc. predominate. The number of cases with perforated ulcer and melaena caused by acetylsalicylic acid is considerable. The frequency of adverse drug reaction for the investigated drugs in "rare" according to WHO standards. It is necessary to assemble more information on adverse drug reactions and every serious case and inform medical doctors and pharmacists as a first step for improving the pharmacovigilance system in Bulgaria.

        Key words: pharmacovigilance, pharmacoepidemiology, adverse drug reactions, drug use