OBJECTIVES: There is a continuous problem in Hungary – and assumable in many other countries – with planning the health insurance pharmaceutical budget. In Hungary there is a substantial gap between the planned and the actual budget resulting in an overspending of the planned pharmaceutical budget. The aim of our study is to analyze the gap between the planned and the actual health insurance pharmaceutical budget. METHODS: Data were derived from the nationwide administrative dataset of the National Health Insurance Fund Administration (OEP), the only health care financing agency in Hungary. We analyzed the difference between the planned and the actual pharmaceutical budget of OEP between 1994-2006. Outcome (overspending rate) is measured with the following formula: the difference between the planned and the actual budget is divided with the planned budget. RESULTS: During the period of 1994-2006 we found significant overspending of pharmaceutical budget of OEP which varied between 3.4-36.6 % of actual pharmaceutical expenditures. The peak of overspending showed a 4 years circle with the highest figures in 1994 (21,5 %), 1998 (32.1 %), 2002 (36.6 %) and 2006 (30.4 %). These 4 calendar years correspond with the time of national political (parliamentary) elections. CONCLUSIONS: We found the highest overspending of the Hungarian pharmaceutical budget in the years of national political elections. It is a scientific evidence for the political influence of the health insurance pharmaceutical budget. The overspending does not relate to any specific political parties or governments because it was a general phenomenon in Hungary between 1994-2006.