OBJECTIVES: For cost-utility analyses, data on health state utilities, as provided by the EQ-5D-3L, is needed but not always available. This study specifies a mapping algorithm from the Beck Depression Inventory (BDI) index to the EQ-5D-3L index adjusted for specific socio-demographic variables for patients with depressive disorders. METHODS: A sample of 1,074 consecutive patients with depressive disorders from a psychotherapeutic outpatient clinic was included in the study. Standardized clinical interviews were applied to establish reliable diagnoses. For the prediction of the EQ-5D-3L index from the BDI index and selected patient socio-demographic characteristics, ordinary least squares regression with robust standard errors was used. Model prediction properties were tested using the root mean squared error and repeated random sub-sampling cross-validation. RESULTS: The BDI index predicted the EQ-5D-3L index with a significant proportion of variance explained. The highest model goodness of fit was estimated for models with the BDI index and age as independent variables. The root mean squared error of the predicted EQ-5D-3L index in the validation samples ranged from 0.225 to 0.228 between the models. CONCLUSIONS: The specified mapping algorithms from the BDI index to the EQ-5D-3L index for patients with depressive disorders are acceptable for usage as approximation in cost-utility analyses. A further validation in independent samples is necessary to obtain more confidence in their performance.