All six were punished for using a diuretic, which can serve as a masking agent for steroids.
The suspended players were running back Deuce McAllister and defensive linemen Charles Grant and Will Smith of the New Orleans Saints; defensive linemen Kevin and Pat Williams of the Vikings; and long snapper Bryan Pittman of the Houston Texans.
"I definitely was not trying to cheat in any form," McAllister told the Associated Press in a phone interview. "I tried to do everything the right way."
A seventh player, the Atlanta Falcons' Grady Jackson, was not suspended. NFL spokesman Greg Aiello said league chief counsel Jeff Pash had asked for additional information from Jackson.
The punishment is an especially harsh blow to Minnesota, which relies heavily on the Williamses in its run defense, which ranks second in the league. The Vikings lead the Chicago Bears by a game in the NFC North with four games left.
Angelo Wright, Pat Williams' agent, said he planned to file a motion in federal court in the next 24 hours, presumably to put off his client's suspension. Tom Condon, the agent for Kevin Williams, said he hadn't determined what course of action to take.
If a player's team makes the playoffs, the player will be eligible to return to the active roster Dec. 29.
Adolpho Birch, the NFL's vice president of law and labor policy, would not disclose during a conference call when the players tested positive. Word of the positive tests leaked in October. Asked why it took until now to hand down the suspensions, Birch said it was "a function of a lot of factors."
Browns:: Quarterback Brady Quinn will have surgery today on his right index finger, which he broke Nov. 17. The procedure, which will likely involve a pin being inserted in Quinn's finger, will require up to 10 weeks of recovery time. The team placed Anderson on the reserve-injured list and signed free-agent quarterback Bruce Gradkowski.
Et cetera: : The Cowboys activated Adam Jones after the NFL lifted the cornerback's suspension. He can return Sunday. ... Quarterback Matt Schaub, who missed the past four games with an injured knee, should return for the Texans on Sunday. ... Patriots backup cornerback Jason Webster will miss the rest of the season with an ankle injury.