To assess the ability of non-certified clinicians to interpret guaiac test results.50 clinicians were shown photographs of 20 guaiac test cards. They were asked to classify these as positive, negative, or uncertain.31 nurses, 4 clinical assistants, 7 emergency attending MDs, 2 resident MDs, and 6 medical students comprised the study group. Mean correct percentages for 15 clearly positive or negative guaiac test cards ranged from 87% to 96% in each of the above groups. Correct results were lower for five of the borderline positive guaiac cards.This study demonstrates that all clinician groups correctly interpreted the guaiac result most of the time, but there was a moderate error rate. This data supports the Joint Commission standard for this particular point of care test; clinicians interpreting guaiac testing should be trained with demonstrated competency.