17 April 1989
World Haemophilia Day was first celebrated in 1989 to increase awareness of haemophilia and to bring the needs of those affected by the disorder to the attention of the wider public. The day is celebrated by haemophilia organisations with wide range of activities around the world, and gives them an opportunity to increase awareness of haemophilia. April 17 was chosen because it coincided with the birthday of the founder of the World Federation of Haemophilia (WFH), Frank Schnabel.  The WFH produces a yearly poster to publicise World Haemophilia Day and help promote haemophilia care.  
References

WhatHealth, World Hemophilia Day 2014 Thu. April 2014 Worldwide, [online], Available at: www.whathealth.com [Accessed: 16 April 2014]