Howard Francis Praagst was born at Brighton, Victoria in 1893 the son of Dr LF Praagst, of Dutch descent, who graduated MB BS Melbourne in 1888 and was a highly respected general practitioner in Brighton.

Praagst was educated at Haileybury College and matriculated in 1910, proceeding to the University of Melbourne where he graduated MB BS with honours in all subjects in 1916. He was a resident medical officer and registrar at the Melbourne Hospital 1916-17. He enlisted in the Navy with the rank of surgeon lieutenant in 1917 and served in the sloop HMAS Fantome for over a year. In World War II he held the rank of honorary major in the Australian Army Medical Corps, performing part-time radiological work at the Repatriation Hospital, Melbourne.

After demobilisation in 1919 he commenced a career in radiology. He was appointed the first full-time resident radiologist at the Melbourne Hospital and held this post until 1923, when he became honorary assistant radiologist. In 1929, it was recognised that radiodiagnosis and radiotherapy, except for the use of x-rays, had little in common and they became separate departments. Praagst took charge of radiodiagnosis with the title of honorary radiographer, a term not changed to radiologist until 1936. He retired in 1947 and was appointed consultant radiologist. In those years, for much of the time the department was short-staffed, and in 1935 measures had to be introduced to limit the exposure to radiation of radiologists doing barium work. These included an embargo on barium examinations of patients with abdominal masses who were to undergo laparotomy.

Praagst became a foundation member of the Association of Radiology of Australia and New Zealand on its inauguration and a foundation Fellow, when it became the College of Radiologists. He was elected a foundation Fellow of The Royal Australasian College of Physicians in 1938. His training in radiology was in the form of an apprenticeship, there being no formal radiological training or examination in Melbourne at that time. In 1923 Praagst entered private practice with Dr LJ Clendinnen. They were joined by Dr R Kaye Scott in 1933 and their partnership continued until 1952 when Praagst retired.

Praagst was a shy retiring man, who did not hold office in the College or in other medical societies or organisations. He attended and participated in radiological meetings and contributed papers mainly on gastroenterology, which was his particular interest. His work was patient and painstaking, with meticulous attention to detail and conscientious care of his patients' interests. He married Kitty Gibbs and for many years they lived quietly at Ferny Creek, in a quite delightful situation in the Dandenong Hills, his home and his garden being his hobbies. There were no children. His activities were restricted by angina in his later years. He died on 9 December 1967, a most highly principled man, greatly respected by his colleagues and friends.