The organisation UNAIDS Pacific is concerned that Fiji's infection rate could increase after the crimes decree introduced harsher penalties for sex workers.
Prostitution is illegal in Fiji and the decree allows police to charge and arrest sex workers, their clients and all those involved in the transaction.
The organisation's coordinator, Stuart Watson, says many sex workers have scattered to the suburbs after police crackdowns, which makes it almost impossible for aid workers to reach them to distribute condoms.
Mr Watson says prostitutes use condoms if they have access to them, but this is slowly changing.
"The Crimes Decree does provide for the possibility that carrying a condom could be used as evidence in court of engaging in sex work. It actually is encouraging people engaged in sex work in Fiji to take risks."
Stuart Watson says sex workers won't stop their trade.