The twins, Evelina and Violetta, were joined at the abdomen and liver, said Yulia Miller, a spokeswoman at the hospital in Barnaul in the Altai Territory in Russia.
"The operation was successful. The babies are feeling well and are staying with their mother," she said.
The operation took 1 1/2 hours to complete and was the fourth successful separation of twins since the collapse of the Soviet Union, RIA Novosti reported.
The two girls may be released from the hospital in 10 days, doctors said.