Police have swooped to shut down two Romanian-run brothels operating in homes in the borough.
Responding to tip-offs from neighbours, officers from Croydon's Antisocial Behaviour team first carried out intelligence gathering and then raided a home in Chatfield Road, Broad Green last month.
They found rooms had been set up to be used solely for sex, and three Romanian women who admitted they were involved in the brothel.
The three have since been served with papers to leave the UK within 30 days.
During the raid, officers also found evidence to suggest a property in Green Lane, Norbury was being used as a brothel.
A raid on Friday August 8 found 18 further people, nine women, six men, all Romanian, who were also served with papers to leave the UK within 30 days.
Both premises are believed to be privately owned, and police are now making enquiries to locate and contact the owners.
PC Chris Duffee, from Croydon Antisocial Behaviour Team said: "Over the past few weeks we've received several complaints from local residents about the address in Chatfield Road and activity going on there. Feedback from locals since we've visited has been very positive and as a result of that visit, we've since discovered a similar situation at an address in Green Lane.
"We would encourage any residents who suspect criminal activity of any type going on in their neighbourhood to get in touch with us, or to contact Crimestoppers anonymously, as we can, and will take action to put a stop to it."
To contact your local Safer Neighbourhoods Team call police on 101 or contact Crimestoppers anonymously by calling 0800 555 111.