colspan=6 | Postponed (rain); Makeup: September 11 as a traditional double-header |- style="background:#bfb" | 145 || September 11 || @ Pirates || 8–6 (12) || Gary Wagner (3–3) || Al McBean (9–12) || Turk Farrell (11) || see 2nd game || 69–76 |- style="background:#fbb" | 146 || September 12 || @ Pirates || 4–6 || Steve Blass (15–5) || Rick Wise (9–13) || Luke Walker (3) || 2,789 || 69–77 |- style="background:#bfb" | 147 || September 13 (1) || Cubs || 3–1 || Chris Short (17–11) || Ken Holtzman (10–12) || None || see 2nd game || 70–77 |- style="background:#fbb" | 148 || September 13 (2) || Cubs || 1–9 || Rich Nye (6–12) || Jerry Johnson (2–3) || None || 5,253 || 70–78 |- style="background:#bfb" | 149 || September 14 || Cubs || 4–1 || Larry Jackson (13–17) || Bill Hands (16–10) || None || 2,251 || 71–78 |- style="background:#fbb" | 150 || September 15 || Cubs || 0–4 || Ferguson Jenkins (18–14) || Grant Jackson (1–6) || None || 4,015 || 71–79 |- style="background:#fbb" | 151 || September 16 || Pirates || 1–6 || Dock Ellis (5–4) || Rick Wise (9–14) || None || 2,087 || 71–80 |- style="background:#fbb" | 152 || September 17 || Pirates || 2–4 || Bob Moose (7–10) || Chris Short (17–12) || Bruce Dal Canton (1) || 2,576 || 71–81 |- style="background:#bfb" | 153 || September 18 || Pirates || 2–1 || Jerry Johnson (3–3) || Bob Veale (13–14) || Gary Wagner (7) || 2,463 || 72–81 |- style="background:#fbb" | 154 || September 20 (1) || Mets || 2–3 || Tom Seaver (15–11) || Gary Wagner (3–4) || None || see 2nd game || 72–82 |- style="background:#fbb" | 155 || September 20 (2) || Mets || 4–5 || Cal Koonce (6–4) || Turk Farrell (4–6) || None || 4,443 || 72–83 |- style="background:#bfb" | 156 || September 21 || Mets || 4–3 || Chris Short (18–12) || Dick Selma (9–10) || Gary Wagner (8) || 1,854 || 73–83 |- style="background:#fbb" | 157 || September 22 || Mets || 2–5 || Jim McAndrew (4–7) || Rick Wise (9–15) || Don Cardwell (1) || 3,259 || 73–84 |- style="background:#bfb" | 158 || September 24 || @ Cardinals || 2–1 || Jerry Johnson (4–3) || Ray Washburn (13–8) || None || 10,530 || 74–84 |- style="background:#fbb" | 159 || September 25 || @ Cardinals || 4–5