Starting April 1, ESPN HD and ESPN2 HD will begin running commercials in high definition for the first time. Together the networks have about 400,000 commercial units available in a given year.

“We are now a one-stop shop for agencies and advertisers that produce their commercials in HD,” said Bryan Burns, ESPN’s VP of strategic planning and business development.

The networks will handle the commercials in the same way they have handled programming in HD for the past few years. The HD networks are simulcasts of the standard-definition networks. That means commercials that are shot in 16-by-9 HD and also “center-cut” so they still look good in analog will play across both channels, regardless of whether the customer receives the networks in HD or analog.

“The same commercial plays to both audiences,” Mr. Burns said. “This is another big chapter in the evolution of the medium.”