"Your Heart Is Your Health", such is the theme of the World Health Day, celebrated on April 7, 1972. That day has been dedicated to the prevention and treatment of heart and circulatory diseases. Its purpose is to stimulate public interest in the problems of heart and circulatory diseases, to promote new measures to solve these problems and to reinforce international co-operation in this field. The World Health Organization, promoter of the World Health Day, is one of the 13 inter-governmental organizations related to the United Nations; its aim is "the attainment by all peoples of the highest possible level of health". When the Organization was created, Canada played an essential role by participating in the preparatory conferences. Moreover, the first Director-General was a Canadian, Doctor Brock Chisholm. Since then, Canada has continued to take part in the assemblies and to contribute to the programmes of the Organization. In Canada, heart and circulatory diseases constitute a serious problem: every year, more than 50% of the deaths result from them, and approximately two and one half million Canadians of all ages suffer from them. In 1956, the Canadian Heart Foundation was created to co-ordinate the work of organizations and individuals interested in reducing sufferings and deaths caused by heart disease. The Foundation is managed by voluntary administrators, including members of the Canadian Cardiovascular Society, its medical counterpart. Among the internationally recognized Canadian innovations, five are noteworthy. First, there are the pacemakers, pioneered in 1948. Thanks to these devices, many thousands of people throughout the world are now able to carry on with their normal activities. Then, artery transplants were developed to relieve severe heart pain, known as angina. This procedure was first undertaken in 1950. Thirdly, the replacement of damaged heart valves by other human valves, which was pioneered in 1938, has been revived during the last five years. The creation of coronary care units in hospitals has been a significant Canadian contribution to the fight against heart disease. The death rate among patients admitted to hospital after heart attacks can be cut by 30% if a coronary care unit is available. Conceived and pioneered in 1962, coronary care units have been established in thousands of hospitals throughout the world. Essentially, they ensure that trained personnel is available within seconds if there is any unwanted change in the patient's heart rhythm or rate. Lastly, in the case of "blue babies", who suffer from one of the major heart defects, the technique for the surgical realignment of the great blood vessels of the heart was developed about 1969. These rewards of research have saved thousands of Canadian lives, and, when they are added to the results of research in other countries, they make heart research a most fruitful investment in the annals of medecine. Because of this vast progress, some heart diseases today are curable, some are preventable, many are controllable. All can be treated.