Two cases of serious intoxication with phenoxy herbicides (MCPP) are reported. 2. Both patients had central nervous system involvement, became unconscious and had an inadequate respiration. Muscle cramps and rhabdomyolysis with renal failure were noted in both. Shortly after admission both patients developed a serious decrease in arterial blood pressure (160/80 mmHg to 80/45 mmHg). In one patient this was demonstrated to be caused by a reduction in peripheral vascular resistance. 3. Plasma concentration of MCPP in patient 2 was 298 mg/l (3-4 h after ingestion). The plasma t1/2 was about 17 h. MCPP plasma elimination probably follows first-order kinetics.