OBJECTIVES To estimate the effect of demographic component in the evolution of public health expenditure of Extremadura in the period 2011-21 METHODS we estimated health expenditure profiles by age and gender in 2011.  Then, we used population projections to calculate future health spending. To obtain those profiles we used data obtained from the information systems of Extremadura. For the primary profile we used the data of frequency by age and gender for this specialised profile obtaining this from the minimum joint data base of the hospital discharge. The profile of the pharmaceutical expenditure by age and gender was obtained from the pharmacy invoice, once the public contribution was deducted. The estimated population in 10 years was obtained from the National Statistic Institute. (INE).  RESULTS aging results in a cumulative annual rate for the period 2011-2021 for public health expenditure growth of 5.34%. The aging effect implies a cumulative annual rate in the period 2011-2021 of 6.43% and a decrease of -0.69% due to the range effect (decrease in population). Of all the segments, the largest increase is in the pharmaceutical costs with an accumulated increase of 8.81%, of which 5,65% is in primary attention and 4,78% in specialised attention.  CONCLUSIONS According to our results, population growth or aging are determining aspects in public health expenditure increase. Using data directly from each region will explain the differences. In the case of Extremadura, the age factor is very important when increasing the pressure of the public health cost, having a special influence in the field of pharmaceutical expenditure and primary attention.