Background: Spiritual distress is present in ~25% of oncology patients. We examined the extent to which this measure is identical to a variety of other measures, such as spiritual well-being, spiritual injury, spiritual pain, and general distress. Methods: Structured interview of oncology outpatients over 12 months, approached non-selectively. The presence or absence of spiritual distress was compared against spiritual pain and two spiritual well-being tools: FACIT-Sp-12 and the Spiritual Injury Scale (SIS). We also examined whether a general distress Visual Analogue Scale sufficed to identify spiritual distress. Other questions concerned demographic and clinical data. Results: Of 416 patients approached, 202 completed the interview, of whom 23% reported spiritual distress. All measures showed significant correlation (Receiver Operating Characteristic, area under the curve 0.79, SIS; 0.68, distress thermometer; 0.67, Facit-Sp-12), yet none were identical with spiritual distress (sensitivity/specificity 64%/79%, SIS; 72%/76%, spiritual pain; 41%/76%, distress thermometer; 57%/72%, Facit-Sp-12). Of the FACIT-Sp-12 subscales, only Peace correlated with spiritual distress. A significant predictor of spiritual distress was patients’ self-evaluation of grave clinical condition (odds ratio 3.3, 95% confidence intervals 1.1-9.5). Multivariable analysis of individual measure items suggests an alternative three-parameter model for spiritual distress: not feeling peaceful, feeling unable to accept that this is happening, and perceived severity of one’s illness. Conclusions: The distress thermometer is not sufficient to identify spiritual distress. The Peace subscale of Facit-Sp-12 is a better match than the measure as a whole. The SIS is the best match for spiritual distress, although an imperfect one.