The canceled dates are Cedar Rapids, Iowa (5/4), Peoria, Ill. (5/5), Green Bay, Wis. (5/7), Fargo, N.D. (5/8) and Sioux Falls, S.D. (5/9).
The band plans to make up the dates, according to its announcement. Ticket-holders can get refund information at the point of purchase.
The follow-up to Slipknot’s self-titled, 1999 debut album is due out in June on Roadrunner Records. The label has not yet specified a date, and an album title has not been announced.
The canceled dates were set to precede a still-intact European outing, scheduled to begin on May 17 in Portugal. The nine-member band will tour the continent through June 3, and will then return to the U.S. for its engagement on this year’s Ozzfest outing.

Slipknot
May
17 - Lisbon, Portugal - Pavilhao Atlantico
18 - Madrid, Spain - Festimad
20 - Milan, Italy - Palavobis
21 - Zurich, Switzerland - Volkhaus
22 - Munich, Germany - Colisseum
24 - Torhout, Belgium -Torhout Festival
25 - Lichtenvoorde, Netherlands - Dynamo Open Air
26 - Keynes, U.K. - National Bowl Milton
28 - Oberhausen, Germany - Turbinehalle
29 - Paris, France - Le Zenith
31 - Bremen, Germany - Pier 2
June
1 - Nuremberg, Germany - Rock Im Park
2 - Vienna, Austria - Libro Music Hall
3 - Cologne, Germany - Rock Am Ring
Ozzfest 2001
June
8 - Tinley Park, IL - World Music Amphitheater
9 - East Troy, WI - Alpine Valley Amphitheater
12, 13 - Indianapolis, IN - Verizon Music Amphitheater
16 - Somerset, WI - Float-Rite Park
18 - St. Louis, MO - Riverport Amphitheater
19 - Bonner Springs, KS - Sandstone Amphitheater
21, 22 - Denver, CO - Mile High Stadium
25 - George, WA - The Gorge
27 - Marysville, CA - Sacramento Valley Amphitheater
29 - Mountain View, CA - Shoreline Amphitheater
30 - Devore, CA - Glen Helen Blockbuster Amphitheater
July
3 - San Antonio, TX - South Texas Verizon Music Amphitheater
5 - Dallas, TX - Smirnoff Music Theater
7 - Atlanta, GA - Hi-Fi Buys Amphitheater
13 - West Palm Beach, FL - Mars Music Amphitheater
14 - Tampa, FL - Zephyr Hills
17 - Charlotte, NC - Verizon Wireless Amphitheater
20 - Bristow, VA - Nissan Pavilion
21 - Camden, NJ - Tweeter Center
24 - Toronto, Ontario - The Docks
26 - Cuyahoga Falls, OH - Blossom Music Center
28 - Burgettstown, PA - Post-Gazette Pavilion
30, 31 - Clarkston, MI - DTE Energy Music Theater
August
3 - Columbus, OH - Polaris Amphitheater
5 - Hartford, CT - Meadows Music Amphitheater
7, 8 - Mansfield, MA - Tweeter Center
11, 12 - Holmdel, NJ - PNC Bank Arts Center