State television said the two sides agreed to restart joint opium poppy yield surveys early this year and cooperate in counter-narcotics training.
U.S. Ambassador Derek Mitchell told reporters after a signing ceremony in the capital, Naypyitaw, that the agreement "is another step forward in our overall relationship. We're very pleased with that."
Police Col. Myint Thein said the survey would provide better information about poppy cultivation and production. "I am confident that it will help our counter-narcotic efforts," he said.
Myanmar is the world's second-largest producer of opium after Afghanistan, accounting for about 25 percent of global poppy production, according to the United Nations.
The last joint opium yield survey was conducted in 2004. U.S. aid for Myanmar's anti-drug efforts has been limited since the military took power in 1988, with most U.S. assistance to the government cut off.
However, relations between Myanmar and the U.S. have improved dramatically since retired Gen. Thein Sein took office as president in March 2011 and instituted a range of political and economic reforms.