After the election of 1994 Borst was appointed as Minister of Health, Welfare and Sport in the Cabinet Kok I, taking office on 3 August 1998.

The following cabinet formation resulted in a continuing coalition agreement between the Labour Party (PvdA) and the People's Party for Freedom and Democracy (VVD) to form a Cabinet Kok II with Borst continuing as Minister of Health, Welfare and Sport and also becoming Deputy Prime Minister, taking office on 3 August 1998.

Borst continued to comment on political affairs as a stateswoman until her death on 8 February 2014 when she was murdered by a mentally unstable man in her home.

Subsequently, Borst worked as a resident physician at the hospital Onze Lieve Vrouwe Gasthuis in Amsterdam where she specialized in pediatric medicine and immunohaematology.

In 1965 Borst started writing her doctoral thesis, while working as a medical scientist at Utrecht University, researching immunohaematology.

In 1976, for instance, when the Democrats 66 had lost nearly all its members and performed particularly bad in the polls, Borst was a volunteer in the promotion and revitalization campaign of the party, led by Jan Terlouw.

In 2001, she implemented a law legalizing Euthanasia in the Netherlands under certain extraordinary conditions, and only when extensive protocols had been followed by the physician, and subject to an obligation of full reporting to a governing body.

[3] Other progressive decisions she is responsible for include: She faced political problems preparing the Dutch medical system for the aging of the population.

[citation needed] In the 1998 elections, Borst succeeded Hans van Mierlo as Lijsttrekker (top candidate) for the Democrats 66.

After the parliamentary inquiry in the El Al Flight 1862 (Bijlmer Plane Crash), Borst faced a motion of no confidence in June 1999.

On 1 September 2015 the Public Prosecution Service released a statement that Borst died from forty-one stab wounds to her head, neck and hands.

[13] On 13 April 2016 Van U. was convicted of the two murders and sentenced to TBS (Involuntary commitment) on the grounds of a diagnosis of chronic paranoid psychosis in the context of schizophrenia.

On 16 March 2017 the Court of Appeal of The Hague declared Van U. only partially unaccountable for the murders and sentenced him to eight years in prison and TBS.