Mulock was Minister for Health from February 1984 to 1986. It was the most demanding period in his 12-year Ministerial career. During most of his tenure he dealt with a bitter dispute with the medical profession. Mulock was Minister for Transport from February 1986 to November 1987. With Education and Health, Transport was one of the top three recurrent spending portfolios. He held all three in succession, the only NSW Minister since Federation to have done so. Mulock served as Attorney-General from November 1987 until the defeat of the Unsworth government in March 1988.