The medical treatment of a 4-year-old female Harbour porpoise which was stranded on the Dutch coast is described. The animal was emaciated on arrival at Harderwijk, and survived for 3 days. During those days the animal regurgitated foreign objects including a large plastic bag, fishing line and algae. Necropsy showed that the animal had 2 large ulcers in the forestomach, and several organs were heavily infected with parasites. Several tissues were examined for heavy metal content, and high levels of mercury were found in the liver and kidneys, but these levels are probably not toxic for marine mammals. The concentrations of total PCB and DDT were relatively low, and these compounds could not have caused death. A virus neutralization antibody titer against a porpoise morbillivirus was found in the blood. Several possible events leading to the animal’s death are discussed.