This series consists primarily of correspondence files maintained in the Prime Minister's Office during Harold Edward Holt's Prime Ministership. The files relate to declined invitations, social and official engagements, congratulations on Holt becoming Prime Minister (January 1966) and his investiture as a Companion of Honour (June 1967), overseas visits, November 1966 general election, 1967 Senate election and general representations. The correspondence covers a wide range of companies, small businesses, service associations, Liberal Party branches, lobby groups, local government, community and religious organisations, professional and sporting bodies, student groups, diplomatic and business associates, Government Ministers and other parliamentarians, personal friends and other individuals. A few files include letters from Holt's wife (Mrs Zara Holt) and his brother (Cliff Holt).

Three presentation gifts are included in the series - a gold bible commemorating the distribution of one million bibles by Gideons International in Australia (1966); a photograph album documenting the visit of President Saragat of Italy (1967); and a leather writing folder relating to Holt's earlier ministerial career in the Immigration and Labour and National Service portfolios.

The present single number system of control was imposed on the series by National Archives. However, the alphabetical order of papers within many of the files (eg general correspondence files) reflects the original filing by Holt's personal staff. The series was discontinued following his disappearance in December 1967.