A 65-year-old woman developed a severe, generalized phototoxic reaction following a visit to a suntan parlor. History taking revealed that she had consumed a large quantity of celery root (Apium graveolens) 1 hour earlier. With the use of thin-layer chromatography, methoxsalen (8-methoxypsoralen) and 5-methoxypsoralen were identified in the extract from a similar celery root. The biologic activity of this extract, as evaluated with the semiquantitative Candida albicans inhibition technique, indicated a total psoralen dose of approximately 45 mg. Substantial amounts of psoralen may be absorbed from vegetables, such as celery, and under unusual circumstances, this may constitute a health hazard.