Following the Labour Party victory in the General Election of February 1974 David Owen was appointed Parliamentary Under-Secretary of Health, being promoted to Minister of State for Health in July; working under Barbara Castle, Secretary of State for Health and Social Services. In this position he was able to supervise the legislation to reform adoption laws, which had been prompted by his introduction of a Private Member's Bill, the Children Bill, in Jan 1974. This bill was built on and improved to become the Children Act 1975 which introduced new regulations for the welfare of children including, as listed in a DHSS press statement in Sep 1976: safeguards against an abrupt move for children in care; strengthening the rights of foster parents seeking to adopt; new grounds for local authorities to assume parental rights and duties; the separate representation of children in certain court proceedings; and a right of access by adopted people to their own birth records . The act was considered by David Owen to be the most constructive legislative contribution I have made to British politics (Owen, Time to Declare p 232).

Further issues in which David Owen became involved as Health Minister included the implementation of the NHS Reorganisation Act 1973 which was due in April 1974; the proposal of regulations to clamp down on private abortion rackets; the tightening of regulations governing the tobacco industry - in advising that tobacco products should come under the 1968 Medicines Act to ensure scientific advice on their health risks; and the appropriation of funds for the World Health Organisation's smallpox eradication campaign. He was also involved in controversial negotiations to phase out private practice, `pay-beds', from NHS hospitals, a Labour manifesto commitment, which involved the setting up of the `Owen Working Party' to produce a new consultant's contract to take into account the consequent changes. Both consultants opposed to the separation of private practice from NHS hospitals, and members of health service unions opposed to private practice took industrial action over the issue. Although pay-bed legislation did reach the statute book under Labour it was subsequently removed by the next Conservative government.