Ruthanasia, a portmanteau of Ruth and euthanasia, is the colloquial name given to the period of free-market neoliberal economic reform conducted under the auspices of the National Party government of New Zealand between 1990 and 1993. As the first period of reform from 1984 to 1990 was known as Rogernomics after the Labour Party Minister of Finance, Roger Douglas, so the second period became known as "Ruthanasia", after the National Party's Minister of Finance, Ruth Richardson.

Many New Zealanders remember Ruthanasia with bitter resentment, as National had fought the 1990 election on a manifesto promising "The Decent Society" and implicitly repudiating the radicalism of the Fourth Labour Government . The Prime Minister, Jim Bolger, defended the move in his memoirs on the grounds that he had been badly misled in the runup to the 1990 election as to the actual state of the New Zealand economy.

Ruthanasia came to an end after the 1993 election, when National's representation was slashed from 67 seats out of 99 (a majority of 45) to 45 seats out of 99 (a majority of 1), and the electorate, by referendum, approved a change of electoral system from First Past the Post to a more proportional system known as MMP, which appeared less likely to concentrate power in the hands of a single party. Some interpret this as a rebuke to the Executive after nine years of broken promises by both parties. Bolger dismissed Richardson from the post of Minister of Finance and she returned to the back benches. Conservative Bolger ally Bill Birch became the new Minister of Finance.