Figures published on Friday suggest that blood clots have killed over 1,000 people in the UK who were under the age of 40 in the last four years.
The data from the Office of National Statistics (ONS) sheds more light on the extent of deaths, with nearly 3,000 people dying from clots under the age of 50.
The condition, known as deep vein thrombosis, took the lives of 1,075 people who were 40 years old and under, between 2005-2008. The condition also claimed the lives of 60 teenagers and children over the same period.
Meanwhile, the deaths of people in their twenties was far higher than expected, with 62 being killed by blood clots - that figure rises to 256 when all deaths between 2005-2008 are accounted for.
Professor Beverley Hunt, Director of Lifeblood and leading haematologist, said: "The statistics are staggering. The UKs medical community needs to urgently explore why these healthy young people are dying in their 1000s from this completely preventable illness.
"We are worried that trainee doctors, nurses and midwives are not being given the basic mandatory training to spot signs of blood clots, and that is something that must be addressed urgently."