Smith and Zeidaks, a pair of juniors expected to play major roles this season, were dismissed by first-year coach Rick Ray on Tuesday for "repeated violations of team rules." That cuts MSU's roster to 10 scholarship players, but only nine will be available this season because of an ACL injury to Jacoby Davis.
"This is an unfortunate situation for Shaun, Kris and our team," Ray said in a statement. "However, players must be held accountable for their actions. Both will remain on scholarship and have the academic support all our other student-athletes receive."
Smith's career was riddled with injuries, going back to his days at Noxubee County High School. In two seasons, the 6-foot-6 guard averaged 1.0 point and 0.6 rebounds in 34 games. He was limited to 10 games last season by a hip injury and suffered a broken finger against Alabama on Feb. 25.
He had gotten healthy this offseason, and Ray raved about Smith during the summer, saying he was shooting well and was doing "everything he's supposed to do." He was expected to battle freshman Fred Thomas for a starting job.
Zeidaks, a 6-8 forward, was never eligible to play for MSU. The NCAA ruled that because he played with and against professionals in his home country of Latvia, Zeidaks would have to sit out all of last season plus the first 11 games of the 2012-13 campaign.
Once he returned, Zeidaks was expected to be a presence in the post.
"I support and respect Rick's willingness to make a difficult decision," MSU athletics director Scott Stricklin said.
The dismissals come less than six weeks before the Bulldogs begin preseason drills. It also continues a trend of roster losses that goes back years.
MSU has only one of its five 2011 signees, forward Roquez Johnson. Two of those played significant roles last season and then transferred: Rodney Hood to Duke, and DeVille Smith to Jackson State.
MSU has seven newcomers on the roster. The three returning players remaining are Johnson, Wendell Lewis and Jalen Steele.