Data from Europe's Venus Express probe suggests that Earth's neighbour may still be able to erupt volcanoes.
Relatively young lava flows have been identified on the planet's surface by the spacecraft's infrared instrument.
The flows show up as having a different composition to the surrounding surface material.
Researchers estimate that they may have been erupted as recently as 2.5 million years ago - and probably much nearer in time than that.
It is even possible these areas are currently active, says Suzanne Smrekar, from the Jet Propulsion Laboratory, California, US, and her colleagues.
The team reports its assessment of lava flows in the Imdr, Themis and Dione regions of Venus in the journal Science.
"This is a significant result," commented Hakan Svedhem, the European Space Agency's Venus Express Project Scientist.
The existence of active volcanoes on Venus has long been debated.
Researchers say a geologically dead planet would be expected to display far more impact craters. Some process on Venus must have reworked the surface. That process is assumed to be volcanism, although it is likely to work at a slow rate.