The US Federal Election Committee says the virtual currency, bitcoin, can be used for donations to political action committees under certain conditions.
In a unanimous vote, the FEC, which enforces US campaign finance laws, said a political committee could accept donations in bitcoins up to an individual limit of US$100 for each election cycle and could also purchase bitcoins.
But the advisory opinion, issued in response to a request for guidance by the Make Your Laws political action committee, said the committee "must sell the bitcoins it purchases and deposit the proceeds into its campaign depository before spending those funds."
The FEC did not approve the use of bitcoins to purchase campaign goods and services.
The agency approved the request by the Make Your Law committee to accept individual bitcoin donations to US$100 for each electoral cycle, require contributors to list their names, addresses, occupations and employers, and affirm they own the bitcoins they are contributing.
Bitcoin, the most popular digital currency, is not backed by any government or central bank, and its value can swing dramatically based on demand. Users can transfer bitcoins to each other online and store the currency in digital "wallets".
The FEC said it concluded that bitcoins were "money or anything of value" under federal election law.
But it acknowledged that "government agencies, courts and others are grappling" with whether virtual currencies should be treated as money.
The US Justice Department warned last year that many virtual currency services did not have the proper controls in place to prevent money laundering and could be used to dodge US laws.