The aim of this work was to validate a previously constructed prognostic score for terminally ill cancer patients in order to determine its value in clinical practice. The Palliative Prognostic Score (PaP Score) was tested on a population of 451 evaluable patients consecutively entered in the hospice programs of 14 Italian Palliative Care Centers. The score subdivided patients into three specific risk classes based on the following six predictive factors of death: dyspnea, anorexia, Karnofsky Performance Status (KPS), Clinical Prediction of Survival (CPS), total white blood count (WBC), and lymphocyte percentage. The performance of the PaP Score index in the training and testing sets was evaluated by comparing mortality rates in the 3 prognostic risk categories. The score was able to subdivide the validation-independent case series into three risk groups. Median survival was 76 days in group A (with a 86.6% probability of 30-day survival), 32 days in group B (with a 51.6% probability of 30-day survival), and 14 days in group C (with a 16.9% probability of 30-day survival). Survival medians were remarkably similar to those of the training set (64 days in group A, 32 days in group B, and 11 days in group C). In the complex process of staging terminally ill patients, the PaP Score is a simple instrument which permits a more accurate quantification of expected survival. It has been validated on an independent case series and is thus suitable for use in clinical practice.