Aim of this study was to describe the real demand for ambulant psychotherapy in Austria. Utilizing estimation models we predicted the demand for ambulant psychotherapy in Lower Austria. The demand was calcula- ted from the general population and prevalence of mentally ill persons as well. Depending on the estimation method used, the demand for psychotherapy in Lower Austria in the year 2013 was between 34.050 and 81.073 (mean = 56751) and 8.561 to 150.796 (mean = 47087) respectively. Due to the insufficient data available, the demand for psychotherapy can only be estimated. It is reasonable to assume that a demand for psychotherapy exists for 47.087 to 56.751 persons. Based on our estimations between 9.580 und 13.747 patients are treated every year.