The assurance of high quality in surgery can be quantified by the outcome. A standardized therapy enables comparison of the quality, both internally and externally. Total quality management (TQM) requires definition, acquisition and analysis of outcome variables. The principles of planning, conducting and analysing could be demonstrated using two quality management studies, "Surgery of benign and malignant goitres" and "Intraoperative neuromonitoring in thyroid surgery". Concerning thyroid surgery, the most important outcome variables are recurrent laryngeal nerve palsy and hypocalcaemia. To determine the frequency of these complications and to identify risk factors, a decentralized data acquisition system was implemented. Software tools ensured a high degree of data safety, data analysis and data consistency despite different methods of documentation. The modular system enabled the rapid and inexpensive development of software tools in this regard. Analysing tools allowed online analysis of the acquired data. The results of the study "Surgery of benign and malignant goitres" with 7361 patients and the study "Intraoperative neuromonitoring in thyroid surgery" with 8900 patients demonstrated that these modular system based software tools could be successfully used in a medical setting. The study "Surgery of benign and malignant goitres" showed a decrease of recurrent laryngeal nerve palsies in patients in whom the recurrent laryngeal nerve was identified. In addition, preservation of at least 2 parathyroid glands led to a decrease of the hypocalcaemia rate. The study "Intraoperative neuromonitoring in thyroid surgery" showed that intraoperative neuromonitoring further decreased the rate of recurrent laryngeal nerve palsies.