The aims of this study were to survey the knowledge and attitudes of Italian health care professionals toward pain and develop a valid instrument to assess pain knowledge of physicians and nurses. A 21-item questionnaire on a Likert scale was given to 4,961 health professionals in 20 hospitals in Italy who volunteered to participate in the study. The results were analyzed psychometrically in three phases: the Principal Component Analysis phase identified two components, of which only the one that had 10 items about pain knowledge and attitudes (PAK) was studied; the Homogeneity Analysis revealed its acceptable internal reliability (Cronbach's alpha=0.72) and confirmed the Likert equidistance of the item options response; and the Confirmatory Factor Analysis proved that it had a very good construct validity. A standardized score was calculated on the PAK questionnaire using the final 10 selected items, considering 100% as the best level of knowledge of pain management and 0% as the worst. The standardized mean score on the whole sample was equal to 52.6% (95% Confidence Interval: 52.3%-53.0%). There was a statistically significant difference (P<0.001) in percentage score between physicians (56.5%) and nurses (51.3%). Knowledge was best among physicians in Anesthesiology and Emergency; this was followed by doctors in Medicine and then surgeons. The knowledge of nurses was almost constant. This scale fills a void by providing a validated instrument for testing the general knowledge about pain treatment of hospital staff. It is brief and can easily be administered to a considerable number of people.