Lagarde stressed she was "extremely encouraged" by the recent progress towards stabilising Ukraine's economy, even against a backdrop of difficult circumstances. The heavily indebted country has suffered amid the turmoil that shifted its sitting government last year.
"The fiscal position is getting stronger, the foreign exchange market has stabilized, and the banking sector is being repaired so that banks are sounder and can start to provide credit again," she said.
"Significant reforms have been launched to bring energy prices to cost recovery levels, with due protection of vulnerable citizens. There has also been progress towards strengthening the social safety net and restoring the social contract in Ukraine."
"In addition, an independent and capable anti-corruption agency with broad powers has been launched and judicial reform has been initiated."
The Washington-based fund agreed on a four-year loan worth $17.5bn (£11.5bn) with Ukraine earlier this year, and so far it's disbursed an initial tranche of $5bn, followed by a further $1.7bn.
But the IMF boss warned that the struggling country's continued commitment to the reforms remained paramount, particularly those surrounding its independent anti-corruption agency.
"Significant challenges remain. It is essential to stay the course of reform and, indeed, deepen the effort. As Ukraine moves forward, it has the full support of the IMF."