The 59-year-old strikeout king was admitted to Round Rock Medical Center on Friday for treatment of recurring symptoms of a pre-existing medical condition. He was transferred to Houston for further evaluation, but Reid Ryan said his father was "feeling great."
"All his tests have come out great," Reid Ryan said. "There's nothing to keep him at the hospital."
Reid Ryan declined to specify the condition, but said it was discovered when his father had double-bypass heart surgery in 2000.
Ryan is still expected to participate in next week's Nolan Ryan Elite Pitching Camp, his son said. The camp starts Monday in Houston.
Ryan struck out 5,714 batters and pitched seven no-hitters - both major league records - in 27 years with the New York Mets, California Angels, Houston Astros and Texas Rangers.
He retired in 1993 and was elected to the Hall of Fame in 1999.
Ryan is a majority owner of two minor league teams: Triple-A Round Rock and Double-A Corpus Christi - both affiliates of the Astros.
CARDINALS: Bing Devine, the St. Louis general manager who helped build Cardinals teams that won three National League pennants and two World Series in the 1960s, died . He was 90.
Devine died at Barnes-Jewish Hospital in St. Louis, said his widow, Mary Devine. He had been ill since Christmas, she said.
"He had surgery, bless his heart," Mary Devine said.
Vaughan P. "Bing" Devine, was general manager of the Cardinals from 1958 to 1964 and again from 1968-78, and was credited with acquiring Hall of Fame players Bob Gibson and Lou Brock. The Brock trade with the Cubs, which cost the Cardinals sore-armed pitcher Ernie Broglio, is considered his best.
Many of the players Devine acquired led the Cardinals to World Series titles in 1964 and 1967 and the pennant in 1968, among them Curt Flood, Dick Groat, Bill White and Julian Javier.