Lithuanian traders and service providers were officially obliged to display their prices both in national currency litas and euros on Friday.
Based on the practice of other countries, it is expected that the dual pricing will reduce the risk of unjustified price increases.
"We do not intend to overlook any cases of abuse and artificial inflation of prices of goods and services in the run-up to the euro," Prime Minister Algirdas Butkevicius said in a statement released earlier this week.
He has repeatedly said the government would maintain tight supervision over preparations for the adoption of euro in the Baltic country.
Many trade and service places in Lithuania started to indicate prices both in litas and euros before the official regulations came into effect.
Lithuania will adopt euro on January 1, 2015. Its two neighbours, Estonia and Latvia, have already joined the 18-member single currency club. (1 U.S. dollar = 2.5 Litas)