|| colspan=6 | Postponed (rain); Makeup: August 28 as a traditional double-header |- style="background:#bfb" | 31 || May 17 || Cardinals || 1–0 (10) || Woodie Fryman (4–4) || Bob Gibson (3–3) || None || 17,034 || 15–16 |- style="background:#bfb" | 32 || May 18 || Cardinals || 3–2 || Larry Jackson (4–5) || Nelson Briles (5–3) || None || 12,941 || 16–16 |- style="background:#bfb" | 33 || May 19 || Cardinals || 4–3 || Turk Farrell (2–0) || Joe Hoerner (2–1) || None || 27,725 || 17–16 |- style="background:#fbb" | 34 || May 21 || @ Cubs || 5–6 || Rich Nye (3–4) || Turk Farrell (2–1) || None || 4,422 || 17–17 |- style="background:#bfb" | 35 || May 22 || Mets || 8–0 || Woodie Fryman (5–4) || Don Cardwell (1–5) || None || 5,717 || 18–17 |- style="background:#bbb" | – || May 23 || Mets || colspan=6 | Postponed (rain); Makeup: September 20 as a traditional double-header |- style="background:#fbb" | 36 || May 24 || @ Cardinals || 1–5 || Steve Carlton (5–1) || Chris Short (2–5) || None || 34,515 || 18–18 |- style="background:#bfb" | 37 || May 25 || @ Cardinals || 1–0 || Larry Jackson (5–5) || Larry Jaster (2–2) || Turk Farrell (5) || 19,432 || 19–18 |- style="background:#bfb" | 38 || May 26 || @ Cardinals || 9–3 || Woodie Fryman (6–4) || Hal Gilson (0–1) || None || 42,446 || 20–18 |- style="background:#bbb" | – || May 28 || Cubs || colspan=6 | Postponed (rain); Makeup: July 17 as a traditional double-header |- style="background:#fbb" | 39 || May 29 (1) || Cubs || 2–9 || Ken Holtzman (4–3) || Chris Short (2–6) || None || see 2nd game || 20–19 |- style="background:#bfb" | 40 || May 29 (2) || Cubs || 8–3 || Rick Wise (4–1) || Rich Nye (3–5) || None || 18,128 || 21–19 |- style="background:#bbb" | – || May 30 || Cubs || colspan=6 | Postponed (rain); Makeup: September 13 as a traditional double-header |- style="background:#fbb" | 41 || May 31 || Reds || 4–5 || Gary Nolan (1–0) || Turk Farrell (2–2) || George Culver (2) || 9,112 || 21–20 |- |- style="background:#bfb" | 42 || June 1 || Reds || 12–0 || Woodie Fryman (7–4) || Milt Pappas (2–5) || None || 10,566 || 22–20 |- style="background:#fbb" | 43 || June 2 || Reds || 3–5