In Latvia, 70 out of 74 MPs voted in favour of the Treaty, while Lithuania's assembly approved it with an 83 to five majority amid 23 abstentions. The document now only requires the signature of each country's president to be finally adopted.
Lithuania, which joined the EU in 2004 together with Latvia and eight other countries, was the first member state to ratify the ill-fated EU constitution in November 2004, months before it was rejected by voters in France and the Netherlands.
The EU welcomed the steps, with the Slovenian Presidency saying that "each ratification is an important step forward on the path to the ultimate goal".
The last of the three EU Baltic states, Estonia, is also expected to follow suit this month.
For it to go into effect on 1 January 2009, the Treaty has to be ratified by all 27 member states. Ireland is the only country to hold a referendum on this issue, scheduled for 12 June (EurActiv 16/04/08).
Apart from Latvia and Lithuania, the Lisbon Treaty has already been ratified by Hungary, Slovenia, Malta, Romania, France, Bulgaria, Poland, Slovak Republic, Portugal, Denmark and Austria.
