After two brief seasons with the Toronto Blue Jays, the New York native was signed by the Astros before the 2002 campaign. At one point, Munro was released by Houston, signed by Minnesota then re-signed by the Astros after Minnesota released him.

Still, he wound up making two starts in the 2004 NLCS against the Cardinals - ironically, the last big league games of his career. In three total seasons with Houston, Munro compiled a 12-16 record with a 4.49 ERA. In the NLCS, he was 0-0 with a 9.00 ERA in seven innings.