Lagarde's comments came at the conclusion of her two-day visit to the kingdom, the first since her appointment as head of the world body.
"This constructive global and regional engagement reflects Saudi Arabia's role as a leader in not only the oil market but also the region and the global economy," said Lagarde.
The IMF chief held talks with Saudi's King Abdullah, the finance minister, the governor of the central bank and representatives of the private sector and civil society, including women leaders.
She commended the Saudis for "preserving financial stability" in the wake of global economic crisis and said the kingdom's "strong economic policies" and government oversight of the financial sector mitigated the effects of the global financial crisis on the Saudi economy.
"Saudi Arabia's policies had an important positive impact on the region and the global economy," said Lagarde, adding that the country has made "significant progress in social development and is now close to the G20 average for most indicators."
She cautioned, however, that challenges remain with "access to housing and job creation."
According to state news agency SPA, the IMF chief's meetings with Finance Minister Ibrahim al-Assaf on Saturday focused on "efforts to resolve" Europe's debt crisis.
Saudi Arabia is a member of the G-20 group of leading economies under pressure to boost their contributions to the IMF's resources for crisis intervention.
The IMF says it wants to raise another $500 billion (380 billion euros), on top of the nearly $390 billion it has available now, to help countries in financial distress.
In an interview published on Friday in Saudi daily Asharq Al-Awsat, Lagarde said the world body would "rely on its major member states" to raise the money, without naming Saudi Arabia.
It remains unclear if the kingdom will agree to increase its IMF contributions.
Saudi Arabia, the world's largest exporter of crude oil, saw a record budget surplus in 2011 of more than $81 billion on the back of high prices on the world market.
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