Audrey Josephine Cahn (17 October 1905 – 1 April 2008) was an Australian microbiologist and nutritionist.
 The daughter of Prof. William Alexander Osborne and Ethel Elizabeth Goodson, a medical practitioner and industrial hygienist, she was born Audrey Josephine Osborne in Melbourne and grew up on the campus of the University of Melbourne. She earned a Bachelor of Agricultural Science at the university in 1929 and, later, received a diploma in dietetics. She first worked as a microbiologist and food analyst for Kraft. 
 Audrey Cahn was employed as chief dietician at St Vincent's Hospital, at the Victorian Mental Hygiene Department and at the Royal Perth Hospital. During World War II, she was chief dietician at the Heidelberg Military Hospital. From 1947 to 1959, she was a dietetics lecturer at the University of Melbourne; from 1959 until 1968, when she retired, she was chief lecturer in nutrition and applied dietetics at the university. She was the first woman to complete the newly established agriculture degree at the University of Melbourne in 1928.  
 She was a founding member of the Dietetics Association. Cahn was among the first experts to recommend reducing fat intake and substituting polyunsaturated fatty acids for saturated fats. She helped conduct a longitudinal study of child growth in Melbourne (1954–1971) which allowed the growth patterns of Australian children to be compared with children in Britain and the United States.Due to her significant contributions to medicine, Audrey Cahn Street in the Canberra suburb of Macgregor was named in her honour.
 The research output of nutritional biochemist, Cahn, was well respected, having completed many studies in the field, including those undertaken during her time at the University of Melbourne from 1947 to 1968. These studies were important in examining the physical properties and energy value of common dietary foods, so that calorie tables could be compiled. Cahn was an early proponent of the need to reduce fat intake and to substitute polyunsaturated fatty acids for saturated fats. With colleagues in the anatomy department, she participated in a 17-year longitudinal study of "Child Growth in Melbourne (1954-71)". The study was compared with similar studies in the United States and Britain and found that Australian children were overweight and inactive compared with their peers elsewhere. She completed a Hospital Certificate of Dietetics at the newly opened Dietetics Unit at St. Vincent's Hospital. Before leaving she rose to the post of Chief Dietician at the hospital. She then took a position at Kraft/Walker and Cheese Factory in Drouin as a microbiologist. She was employed as the first Chief Dietician for the Victorian Mental Hygiene Department followed, before spending a year at the Royal Perth Hospital. 
 During World War II, she enlisted in the Australian Army Medical Women's Service on 11 February 1943. As part of the Australian Army Medical Corps she became Chief Dietician at the Heidelberg Military Hospital. Before her discharge on 13 September 1946 Audrey had obtained the rank of Major. After the war, Audrey obtained a position as Lecturer (1947) and then Senior Lecturer (1959) in Nutrition and Applied Dietetics. 
 In 1930, she married Leslie Cahn, an architect, they had two children but the marriage ended in divorce. 
 Audrey Cahn died in Canberra at the age of 102.