Purpose: This study examined symptoms reported by patients after open-ended questioning vs those systematically assessed using a 48-question survey. Materials and methods: Consecutive patients referred to the palliative medicine program at the Cleveland Clinic Foundation were screened. Open-ended questions were asked initially followed by a 48-item investigator-developed symptom checklist. Each symptom was rated for severity as mild, moderate, or severe. Symptom distress was also evaluated. Data were collected using standardized pre-printed forms. Results: Two hundred and sixty-five patients were examined and 200 were eligible for assessment. Of those assessed, the median age was 65 years (range 17-90), and median ECOG performance status was 2 (range 1-4). A total of 2,397 symptoms were identified, 322 volunteered and 2,075 by systematic assessment. The median number of volunteered symptoms was one (range zero to six). Eighty-three percent of volunteered symptoms were moderate or severe and 17% mild. Ninety-one percent were distressing. Fatigue was the most common symptom identified by systematic assessment but pain was volunteered most often. The median number of symptoms found using systematic assessment was ten (0-25). Fifty-two percent were rated moderate or severe and 48% mild. Fifty-three percent were distressing. In total, 69% of 522 severe symptoms and 79% of 1,393 distressing symptoms were not volunteered. Certain symptoms were more likely to be volunteered; this was unaffected by age, gender, or race. Conclusion: The median number of symptoms found using systematic assessment was tenfold higher (p<0.01) than those volunteered. Specific detailed symptom inquiry is essential for optimal palliation in advanced disease.