The aim of this study was twofold: to examine the individual quality of life of drug addicted patients after being admitted to a drug withdrawal programme in a psychiatric hospital in Switzerland, and to check whether the individual quality of life changes over a period of three weeks. Within three days following admission, thirty patients (23 men, 7 women) were interviewed, using the half structured instrument Schedule for the Evaluation of Individual Quality of Life: a Direct Weighting Procedure for Quality of Life Domains (SEIQoL-DW). Three weeks later, 16 patients (who were still participating in the drug withdrawal programme) were interviewed for a second time. The 46 interviews were analysed by means of qualitative content analysis according to Morse and Field (1998). In the 30 interviews that were conducted within the first three days following hospital admission, 269 individual quality of life domains (QLD) were described, from which 37 categories of QLD could be derived, which in turn were classified into nine main themes. In the second round of interviews conducted after three weeks in hospital, the QLD categories and the main themes remained nearly identical to those derived from the first round. Only one new category of QLD, <<structural conditions>>, could be identified and was assigned to the main QLD "distress factors". The rankings of some QLDs changed. The median of the Global Quality of Life (GLQ) index of all 30 patients amounted to 48.5 out of 100 points. The initial value for 16 patients who were interviewed for a second time was 57.7 while the value for the 14 drop outs amounted to 39.9. After three weeks, the median of the GLQ of the remaining 16 patients increased from 57.7 to 63.1. Compared to a healthy population, drug addicts have a lower quality of life, while compared to other psychiatric groups similar quality of life can be observed. The SEIQoL-DW method was well accepted among patients without distressing them. This study shows that the quality of life of drug addicts is individual, multi-dimensional, dynamic and complex.