Several hundred Lithuanians were protesting in the capital against the government's plan to proceed with shale gas exploration.
The demonstrations in Vilnius were fueled by a recent decision to issue an exploration license to U.S. oil company Chevron in western Lithuania.
Protesters on Tuesday banged drums and held signs reading "Chevron, go away!" and "No American capitalists on Lithuanian soil." Critics say exploring for shale gas creates a significant environmental risk in the heavily forested areas close to the Baltic Sea.
But supporters argue shale gas represents a rare opportunity to decrease energy dependency on Russia, which currently supplies all of the country's gas.
Lithuania could have 50 billion - 60 billion cubic meters of shale gas reserves, or about 20 years' worth of gas at current rates of consumption.