Di-(2-ethylhexyl)phthalate (DEHP) taken orally by two volunteers (30 mg each) was excreted in the urine to the extent of 11 and 15% of dose. After enzymic hydrolysis the urinary metabolites (derivatives of mono (2-ethylhexyl)phthalate) were methylated and identified by g.l.c.-mass spectrometry (C.I.), and the quantitative distribution of conjugated and free metabolites determined. DEHP taken by the same volunteers over a period of four days at doses of 10 mg daily gave no evidence of accumulation; 15 and 25% of the total dose was recovered in the urine.