The office of Zambia President Michael Sata said the president left the country for a "medical checkup."
The brief notice released Monday did not say where Sata went nor when he may return.
Concerns about the 77-year-old president's health have mounted in Zambia since he traveled to Israel for medical treatment in June and then made no public appearances for nearly three months.
The president attended the opening of parliament in September, but failed to appear last month for a scheduled address to the U.N. General Assembly in New York.
New York police told VOA Sata was treated at his hotel by U.S. State Department doctors. Zambia's Vice President Guy Scott disputed reports Mr. Sata was ill, saying the president's health was "entirely normal."
President Sata has led Zambia since winning the 2011 election.