Background: There is a wide variation in the quality of information available to patients on the treatment of the diseases afflicting them. To help patients find clear and accessible information, many scales have been designed to evaluate the quality of health information, including the Patient Education Materials Assessment Tool; the Suitability Assessment of Materials for evaluation of health-related information for adults; and DISCERN, an instrument for judging the quality of written consumer health information on treatment choices. These instruments are primarily in English. Few of them have been translated and adapted into simplified Chinese tools for health information assessment in China. Objective: This study aimed to translate and adapt DISCERN into the first simplified Chinese version and validate the psychometric properties of this newly developed scale for judging the quality of patient-oriented health information on treatment choices. Methods: First, we translated DISCERN into simplified Chinese using rigorous guidelines for translation and validation studies. We tested the translation equivalence and measured the content validity index. We then presented the simplified Chinese instrument to 3 health educators and asked them to use it to assess the quality of 15 lung cancer–related materials. We calculated the Cohen κ coefficient and Cronbach α for all items and for the entire scale to determine the reliability of the new tool. Results: We decided on the simplified Chinese version of the DISCERN instrument (C-DISCERN) after resolving all problems in translation, adaptation, and content validation. The C-DISCERN was valid and reliable: the content validity index was 0.98 (47/48, 98% of the items) for clarity and 0.94 (45/48, 94% of the items) for relevance, the Cronbach α for internal consistency was .93 (95% CI 0.699-1.428) for the whole translated scale, and the Cohen κ coefficient for internal consistency was 0.53 (95% CI 0.417-0.698). Conclusions: C-DISCERN is the first simplified Chinese version of the DISCERN instrument. Its validity and reliability have been attested to assess the quality of patient-targeted information for treatment choices.