The nature of phase I clinical trials in cancer patients raises many ethical issues. An area of major importance is the quality of life (QoL) of these patients. However, there is limited information available concerning the impact of phase I clinical trials on the QoL of patients with cancer. The primary aim of this study was to examine the QoL of cancer patients participating in phase I clinical trials. A descriptive triangulation approach was employed. The secondary aim was to determine the acceptability of the Schedule for the Evaluation of Individual Quality of Life - Direct Weighting (SEIQoL-DW) within this group of patients. SEIQoL-DW is a relatively new tool which investigates the areas identified by individual patients as important to their QoL. Cancer patients (n=15) participating in phase I clinical trials were interviewed using the SEIQoL-DW tool. During this interview patients nominated the areas of life important to them and rated their relative weighting and current status. Cues nominated were described and results analysed using non-parametric statistical tests. The results showed that health and family were particularly important to patients in relation to their QoL. The importance of an individualized approach in the measurement of QoL was evident. SEIQoL-DW was found to be acceptable and practical to use in cancer patients participating in phase I clinical trials. Recommendations for practice were drawn and suggestions made for further research.