|| 6,885 || 13–20 |- style="background:#fbb" | 34 || May 17 || @ Pirates || 2–5 || Bob Moose (3–3) || Steve Carlton (4–6) || Jim Rooker (4) || 6,885 || 13–21 |- style="background:#fbb" | 35 || May 18 || Cubs || 2–9 || Ferguson Jenkins (4–3) || Dick Ruthven (1–3) || None || 10,067 || 13–22 |- style="background:#bfb" | 36 || May 19 (1) || Cubs || 3–0 || Ken Brett (2–1) || Burt Hooton (5–3) || None || see 2nd game || 14–22 |- style="background:#fbb" | 37 || May 19 (2) || Cubs || 6–7 || Bob Locker (5–1) || Jim Lonborg (2–5) || Jack Aker (8) || 27,569 || 14–23 |- style="background:#bbb" | – || May 20 || Cubs || colspan=6 | Postponed (rain); Makeup: July 31 as a traditional double-header |- style="background:#fbb" | 38 || May 21 || Pirates || 4–5 || Steve Blass (2–2) || Mac Scarce (0–2) || Dave Giusti (3) || 9,010 || 14–24 |- style="background:#bfb" | 39 || May 22 || Pirates || 7–4 || Wayne Twitchell (2–1) || Dock Ellis (3–5) || None || 11,617 || 15–24 |- style="background:#bbb" | – || May 23 || Pirates || colspan=6 | Postponed (rain); Makeup: August 4 as a traditional double-header |- style="background:#bfb" | 40 || May 25 || @ Padres || 8–1 || Ken Brett (3–1) || Fred Norman (1–6) || None || 26,615 || 16–24 |- style="background:#bfb" | 41 || May 26 || @ Padres || 4–0 || Steve Carlton (5–6) || Mike Caldwell (2–6) || None || 7,260 || 17–24 |- style="background:#bfb" | 42 || May 27 (1) || @ Padres || 4–3 || Wayne Twitchell (3–1) || Bill Greif (3–5) || Barry Lersch (1) || see 2nd game || 18–24 |- style="background:#bfb" | 43 || May 27 (2) || @ Padres || 6–4 || Jim Lonborg (3–5) || Steve Arlin (2–2) || Mac Scarce (5) || 9,983 || 19–24 |- style="background:#fbb" | 44 || May 28 || @ Dodgers || 1–5 || Andy Messersmith (5–4) || Dick Ruthven (1–4) || None || 15,300 || 19–25 |- style="background:#fbb" | 45 || May 29 || @ Dodgers || 3–9 || Tommy John (4–2) || Ken Brett (3–2) || Jim Brewer (5) || 12,350 || 19–26 |- style="background:#fbb" | 46 || May 30 || @ Dodgers || 4–9 || Claude Osteen (5–3) || Steve Carlton (5–7) || None || 15,462 || 19–27 |-