Margaret E. Billingham (née Macpherson) (September 20, 1930 - July 14, 2009) was a pathologist at Stanford University Medical Center, who made significant achievements in the early recognition and grading of transplant rejection following cardiac transplantation, known as 'Billingham's Criteria'. She also described chronic rejection and techniques in heart endomyocardial biopsy. Born in Tanzania, and educated in Kenya and subsequently qualified from the Royal Free Hospital in London, Billingham found herself developing rejection pathology and eventually becoming director of cardiac pathology at Stanford University Medical Center. She settled in the United States with her husband, who was also a doctor, and their two children, and died there in 2009. Early life Billingham's father was posted as a British diplomat, to Tanzania. She was then born in 1930 in Tanga, Tanzania, and then educated at Loreto School in Kenya. She had a sister, Shirley Anne. Moving to England, she gained admission to the Royal Free Hospital in London to study medicine, subsequently graduating in 1954. Family She met her future husband John Billingham while they were both doing their junior house posts. They married in 1956, while they were both employed at Hampstead General Hospital. In 1963, they then emigrated to Houston, Texas, with their two sons, Robert and Graham. Two years later, in 1965, they moved to San Francisco Bay. Her husband became chief of the life sciences division at Ames Research Center. Medical career In 1966, Billingham started a 2-year postdoctoral researcher at Stanford. Originally in cardiopulmonary medicine, she then switched to pathology in 1968. By 1988, Billingham was professor in pathology at Stanford. She worked closely with Philip Caves at Norman Shumway's cardiac transplantation unit, where they developed the technique for assessing and monitoring acute organ rejection following heart transplant surgery. Serial biopsies, taken from transplanted hearts within the recipients, were taken using a newly developed bioptome, percutaneous transvenous endomyocardial biopsy. The histological samples were examined in the pathology laboratories for early signs of rejection, allowing early treatment interventions. The timing of her work coincided with the excitement in early heart transplant surgery, with Norman Shumway performing the first heart transplant in the United States in 1968. She was at Stanford at a time when Stanford was leading cardiac transplantation research on an international platform and when places like Stanford had relatively few leading female scientists. The grading system was soon adopted as the standard method for examining