In 1990, Zinsou returned to Benin after his 17-year exile. He opposed the new constitution in the referendum of 2 December 1990 but was unsuccessful. Zinsou was a mediator in the Democratic Republic of the Congo during that country's civil war in the late 1990s; he arrived in Kinshasa on 20 September 1999, along with fellow mediator Padre Matteo Zuppi, and met with President Laurent-Désiré Kabila.