The traffickers and consumers were followed for about three months by the Bucharest antidrug police brigade, which was collecting evidence to bring down a drug dealing ring thought to be one of the biggest in the city.
Investigators said group members sold heroin in Bucharest and nearby counties of Ilfov and Giurgiu.
Police tracked down 13 people aged 19 to 52 and arrested nine of them following searches. Police found heroin, methadone, cannabis, mobile phones and prepaid cards, money thought to be gained from selling drugs, and diverse materials used to wrap and consume drugs.