He smiled when someone told him after the game he fanned seven in a row, the most by a Red since John Smiley had seven straight against Colorado in 1996.
"I knew I threw a lot of strikeouts," Ramirez said. "I didn't know how many I had. That's nice."
It was the most consecutive strikeouts since Kerry Wood of the Chicago Cubs fanned seven straight against Atlanta in April 2004.
"I felt very good, my concentration was very good," Ramirez said.
Adam Dunn and Ken Griffey Jr. homered and Ramirez also had an RBI double. Dunn went 3-for-3 with four RBI and Ramirez (4-6) went 6 2/3 innings to win for the first time since June 25, allowing six hits and striking out eight.
"Those seven strikeouts, against major league players, that's a pretty awesome feat," Cincinnati manager Jerry Narron. "He had real good velocity on his fastball and his curveball was outstanding."
Lance Berkman, Luke Scott and Eric Munson had RBI singles in the eighth off Reds reliever Billy Bray to make it 6-4, but Todd Coffey came on and struck out Adam Everett to end the inning.
The Astros dropped six games under .500 (48-54) and six games behind the Reds in the crowded NL wild card race.
"We're just not getting on a roll," Houston manager Phil Garner said. "We're not putting anything together."
Astros starter Taylor Buchholz (6-9) lasted only two innings as the Reds hammered him from their first at-bat.
Ryan Freel ripped Buchholz's third pitch into the right-field corner for a double and Dunn followed with a liner to left-center for his eighth RBI since the All-Star break.
Griffey then hit his 20th homer of the season and the 556th of his career, a towering two-run drive over the Astros' bullpen in right-center.
That was all the run support Ramirez needed.
"Any time you do that for a pitcher, then you let him go out and make his pitches," Griffey said. "It makes it a lot easier for anybody."
The Reds didn't let up in the second.
Royce Clayton led off with a hard single to left and stole second. Ramirez, a career .100 hitter (3-for-30), then hammered a double -- his first -- to the wall in right. Clayton scored, giving Ramirez his second career RBI.
Dunn, hitting .340 since June 25, then crushed a 3-2 pitch over the fence in center, his 31st. It was Dunn's sixth straight hit in the series after he tied a career high with four hits on Wednesday.
"I just didn't really have a clue where the ball was going," said Buchholz, who threw only 39 pitches. "I was just missing right down the middle, up belt-high. And they were hitting it every time."
Willy Taveras pinch hit for Buchholz in the second, ending the rookie right-hander's shortest outing in 18 career starts. Taveras blooped an RBI single to center to cut Cincinnati's lead to 6-1.
Matt Albers, called up on July 20, relieved Buchholz and retired the Reds in order in the third and fourth. He pitched five scoreless innings, retiring 15 of the 20 batters he faced.
"The first pitch I threw got hit pretty hard, but it went right at a guy," Albers said. "I was like, 'OK, just keep it up and get outs quick."'
The Astros never mustered much against Ramirez, who retired 13 straight after Taveras' hit, striking out the side in the fourth and fifth. Craig Biggio battled Ramirez for 16 pitches, fouling off 11, before striking out on a belt-high fastball to end the fifth.
"That at-bat against Biggio was an outstanding duel," Narron said. "To come away with that one was excellent."
Chris Burke popped out to Clayton leading off the sixth, snapping Ramirez's strikeout string. Berkman grounded out and Aubrey Huff flew out to end the inning after just five pitches from Ramirez.
"He mixed up his pitches well," Reds catcher Javier Valentin said.
Biggio doubled off Reds reliever Gary Majewski to start the Astros' late rally. Burke was hit by a pitch, Bray relieved Majewski and Berkman hit an RBI single off shortstop Clayton's glove. Berkman then left the game, aggravating a left groin injury he suffered on Sunday.
After an out, Scott and Munson had consecutive RBI singles, chasing Bray after two-thirds of an inning. But the comeback stopped there.
"It's always a letdown when you don't win a game," Munson said. "When you get close like that, is it more of a letdown? I mean, I don't know. We have to try to forget about it and come back tomorrow."
- Griffey recorded his 1,591st RBI, tying Andre Dawson for 24th all-time.
- Narron earned his 100th win as Reds manager.
- The Reds improved to 36-10 when they score first, the best percentage in the NL.
- The Astros have lost seven of nine to the Reds this season.
- The bullpen's scoreless streak was the Astros' longest since 1989, when they went 29 1/3 innings.