Health workers have warned that Cambodia's success in reducing its rate of HIV and Aids may be at risk.
The US-based Results for Development Institute says that prevention and treatment programmes are too reliant on overseas donors.
If that money stopped coming through, infections and deaths might rise.
Cambodia used to be the HIV blackspot of Southeast Asia - in the late 1990s there were 15,000 new infections every year.
But in recent years, Cambodia has been the star performer, where the rate of new infections has fallen to around 2,000.
The country is also renowned for its treatment programmes for HIV-positive people.
More than nine out of 10 patients eligible for anti-retroviral drugs are getting the medicine.
But there may yet be unwelcome twists in both those success stories.
Anti-human trafficking laws have resulted in the closure of many brothels.
That has made it more difficult to reach sex workers to encourage the use of condoms.
And the drug treatment programmes are almost totally funded by foreign donors.
Robert Hecht of the Results for Development Institute says that is an unhealthy position.
"Foreign aid is quite uncertain, hard to predict.
"Cambodia is in a position to manage the costs of its Aids programme because it has been successful in reducing new infections.
"It has a good opportunity to expand its share of the total funding pot and in that way reduce its dependence on the outside sources of financing," he said.
Mr Hecht says that gradually reducing donations would allow Cambodia to take more control of its HIV/Aids programmes.
The government has welcomed the report.
It says it will help to "sharpen its strategies".