"It has been refreshing to see great progress in so many aspects that worried us in February. I trust this positive trend will continue," UN assistant secretary general for humanitarian affairs Catherine Bragg told a news conference.
"It is important to celebrate the achievements to date, however we must not neglect the continuing humanitarian needs."
The United Nations on Monday appealed to donors for 378 million dollars (256 million euros) in aid for 2010, saying the humanitarian situation in the country remains "fragile".
Bragg met Prime Minister Morgan Tsvangirai on Wednesday and government ministers. She is expected to meet President Robert Mugabe later Wednesday.
Bragg toured UN projects in central Zimbabwe, visiting clinics and communal farmers benefiting from seeds donated by aid organizations.
Since the formation of the unity government of one-time rivals Mugabe and Tsvangirai, the former opposition leader, hospitals have re-opened and basic services have improved.
But the recovery still has far to go, after much of Zimbabwe’s basic infrastructure fell apart during a decade of political crisis and economic collapse.
Last year cholera killed over 4,200 people while more than 100,000 were infected by the disease. This year only a handful of cases have been reported.