Canceled are the group's performances in Indianapolis on May 27; Cleveland on May 28; Boston on May 29; and St. Louis on May 30.

"After being forced to cancel a show on April 15th at Delta State University, and continuing to feel exhausted while finishing the tour, John Popper meet with his doctors in New York where he had to have minor surgery and was told he must rest for at least 3-4 weeks before he can tour again," the group said in a statement.

The group did not specify what type of surgery Popper had, nor what necessitated the surgery.

"John's health is great and he is going to be fine, his doctors said," the statement continued. "He will soon feel better than has felt in a long time. Blues Traveler will be touring all summer and in the fall and they will play the cities where they have cancelled. We apologize for any inconveniences and we know fans are disappointed, as is the band, but the good news is John is fine and Blues Traveler will be touring again soon."

To that end, Blues Traveler has scheduled a short series of July concerts, beginning with its traditional July 4 performance at Red Rocks Amphitheatre in Morrison, CO. Details are shown below.

Last November, the group issued "Thinnest of Air: Live from Red Rocks," a two-DVD set that features the group's July 4, 2003 show at the Denver-area venue.

Blues Traveler's most-recent studio album is last year's "Truth Be Told," a 12-track set that the group recorded with producer Don Gehman (Hootie & the Blowfish, John Mellencamp).