Intoxication with vitamin D may lead to severe hypercalcemia, renal failure and occasionally to death. An increasing amount of vitamin D supplement is sold over-the-counter (OTC) or over the internet. Here we present a case were a person obtained vitamin D over the internet and administered 50 000 IE daily to his father for a period of six months, in the pursuit to stop or reverse the progression of a vascular dementia. The treatment resulted in a severe hypercalcemia and recurrent hospitalizations. In cases with an unexplained hypercalcemia, being associated with high levels of 25(OH)-vitamin D3 the possibility of intake of D-vitamin sold without a doctor's prescription should be investigated.