The carrier says that it intends to withdraw the 747-200s, of which it has around half a dozen, from passenger service by 2010.
"These aircraft will be converted into a freighter version," says the airline. "They will serve to develop Transaero's cargo traffic."
The first of six secondhand 747-400s is due to enter service before the end of the year.
Moscow-based Transaero operates virtually an all-Western fleet, although this does not include dedicated freighters. The airline's 747 complement also includes at least one 747-300.
Transaero became the first Russian airline to introduce passenger 747s into regular service when it started operating the type two years ago. The jets operate services to South-East Asia, the Caribbean and holiday destinations in the Mediterranean.
Meanwhile, Russia's second 747 operator Tesis has acquired a second 747-200 freighter.