Hunter Pence went 3-for-3 with a home run and two RBI for Houston, while Humberto Quintero also collected three hits.
Astros starter J.A. Happ gave up five runs on nine hits over six innings.
Andrew McCutchen belted a two-run homer and Pedro Alvarez added a solo blast for the Pirates. Brian Burres was tagged for six runs and 10 hits in five full frames.
Enerio Del Rosario pitched another scoreless inning, although he did give up two hits.Gustavo Chacin had the most impressive inning of the day, leaving the PIrates hitless with a strikeout, as he continued the battle against Ryan Rowland-Smith and Fernando Abad for the lefty specialist role.
The Astros will be back in Kissimmee tomorrow as they host the Tampa Bay Rays, who hopefully will not wound any Astros starters with a line drive to the head as Manny Ramirez did to Roy Oswalt today.