OBJECTIVES: To establish the number of psychotherapists with professional backgrounds; psychotherapeutic provision and its cost; change in cost in case of integration of non-medical psychotherapy into the mandatory minimum health care benefit. METHODS: A population-based survey using computer-assisted telephone interviews in a randomly selected sample of medical and non-medical psychotherapists (NMP), stratified by professional status and language regions. RESULTS: 1,633 psychiatrists, 2,332 general practitioners and 2,616 NMP provide psychotherapy in Switzerland. NMP by training: 1,674 (64%) hold a university degree in psychology; 539 (21%) hold a professional school degree in psychology; and 403 (15%) have various backgrounds. In 2000, 146,000 patients utilised 4.52 million hours of medical psychotherapy, which cost CHF 579 million, CHF 396 million of which were reimbursed by mandatory health insurance (MHI). Reimbursement of NMP by MHI would result in additional expenditures of CHF 102-252 million. CONCLUSIONS: NMP provide 46% of psychotherapy which is currently partly reimbursed by the MHI. An integration of NMP into the MHI benefit package would incur additional costs to MHI of CHF 102-252 million.