OBJECTIVES: To determine if the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) can satisfactorily predict EQ-5D, SF-6D and 15D utilities. The QLQ-C30 measures health-related quality of life (HRQOL) using a global scale, five functional scales and eight symptom scales/items and like most HRQOL instruments provides a profile of scores instead of an overall preference-based index, precluding its use in cost-utility studies. METHODS: A stratified sample (N=48) of gastrointestinal cancer patients on chemotherapy was interviewed. The survey contained the QLQ-C30, the SF-36, two multi-attribute utility instruments (EQ-5D and 15D) and socio-demographic and disease-related questions. Validity of QLQ-C30 scales was assessed by testing a priori hypotheses that they would be moderately or strongly correlated with SF-36 scales measuring similar HRQOL dimensions and that younger subjects and those not reporting comorbid conditions would have better scores. Linear regression analyses identified the extent to which QLQ-C30 scales could predict EQ-5D, SF-6D and 15D utilities. RESULTS: Pearson’s correlations between similar QLQ-C30 and SF-36 scales ranged from 0.69 to 0.89 (P<0.001). Subjects with coronary heart disease had worse scores on all QLQ-C30 functional scales (T-test, P<0.05 for four scales), as did older subjects as well (ANOVA, P<0.05 for five scales). QLQ-C30 global, functional and symptom scales were significant predictors of utility scores elicited from standard instruments. Specifically, three scales were significant (P<0.05) predictors of EQ-5D utilities, six scales (P<0.05) of SF-6D utilities and four scales (P<0.001) of 15D utilities and explained large portions of variance (adjusted R2 was 0.610, 0.833 and 0.912 respectively). Robustness of results was tested and confirmed in patient subgroups with differing HRQOL. CONCLUSIONS: Preliminary evidence has been provided supporting the appropriateness mainly of the 15D and SF-6D instruments in cancer-specific cost-utility studies, although further studies involving larger and more diverse patient samples are encouraged.