The medical team, which worked from two clinics in Mutoko and Harare, denies the charges.
The Christian volunteer health team from California includes a doctor, two nurses and a community worker.
They mainly looked after Aids orphans and HIV-positive patients, the US embassy said.
A police spokesman told the state-controlled Herald newspaper that the six were arrested “for questioning in connection with practising without a premises licence and dispensing medicines without the supervision of a pharmacist”.
The health workers are members of a Baptist church in Oakland. A minister from the church, Teophous Reagans, told the Associated Press that volunteers from the congregation had worked in Zimbabwe for 10 years.
He said this was the first time questions about a team’s licensing had been raised.
Zimbabwe has one of the worst HIV infection rates in the world.
Source: news24.com