Medvedev, addressing a joint news conference with Obama at the White House, said he hoped work on Russia's WTO membership would be finalised by the end of September.
The leaders also announced expanded co-operation between their countries in several key areas, including intelligence sharing and counter-terrorism. Economic ties between Moscow and Washington look set to get closer as a result of agreements struck during the meetings.
One decision flagged up by Obama as evidence of improved relations was Medvedev's decision to reverse a ban on poultry imports from the US.
"We've reached an agreement that will allow the United States to begin exporting our poultry products to Russia once again," Obama said.
American poultry had been banned by Moscow in January because it is treated in chlorinated water, a practice banned in Russia.
Al Jazeera's Nick Spicer, reporting from Washington, said that relationship between the two powers had grown closer in recent months.
"Over the past few months there have been significant changes, significant steps forward. The biggest impetus to change on the Russian side has been the global economic crisis, which made Russia realise it needs to reach out and engage with the world in new ways," he said.
"There are significant steps forward as well with regards to the Start [Strategic Arms Reduction] treaty when both countries signed up to reducing their nuclear arsenals."
But our correspondent noted there were still lingering tensions between the two powers, referring to disagreements over Georgia.
"I don't think there will be a complete meeting of minds," he said.
Obama admitted as much in the news conference, but said that the two leaders were able to "speak candidly" about their differences, describing Medvedev as a "solid" and "reliable" partner.
Medvedev, who started his visit to the United States with a tour of high-technology companies in California's Silicon Valley, also met business leaders to encourage them to invest in Russia.
Russia has attracted $265.8 billion in foreign investment since the fall of the Soviet Union in 1991, however the US accounted for just three per cent of that. US bilateral trade with Russia was just $18.4bn last year.