76–72 |- style="background:#bfb" | 150 || September 17 || @ Cardinals || 7–5 || Steve Carlton (16–11) || Darold Knowles (2–5) || Tug McGraw (16) || 6,479 || 77–72 |- style="background:#bfb" | 151 || September 18 || @ Cardinals || 5–3 (10) || Tug McGraw (4–3) || Dan O'Brien (1–1) || None || 7,340 || 78–72 |- style="background:#fbb" | 152 || September 19 (1) || Pirates || 6–9 || Kent Tekulve (10–7) || Rawly Eastwick (3–5) || Grant Jackson (14) || see 2nd game || 78–73 |- style="background:#bfb" | 153 || September 19 (2) || Pirates || 6–5 || Jack Kucek (1–0) || Enrique Romo (10–5) || Kevin Saucier (1) || 30,566 || 79–73 |- style="background:#bfb" | 154 || September 20 || Pirates || 2–1 || Randy Lerch (10–12) || Kent Tekulve (10–8) || None || 16,299 || 80–73 |- style="background:#bbb" | – || September 21 || Expos || colspan=6 | Postponed (rain); Makeup: September 22 as a traditional double-header |- style="background:#bfb" | 155 || September 22 (1) || Expos || 9–8 (10) || Ron Reed (12–8) || Dale Murray (5–10) || None || see 2nd game || 81–73 |- style="background:#fbb" | 156 || September 22 (2) || Expos || 2–8 || David Palmer (10–2) || Dickie Noles (3–4) || None || 35,186 || 81–74 |- style="background:#fbb" | 157 || September 23 || Expos || 4–7 || Bill Lee (16–10) || Nino Espinosa (14–12) || None || 26,507 || 81–75 |- style="background:#fbb" | 158 || September 24 || Cardinals || 2–7 || Pete Vuckovich (15–10) || Randy Lerch (10–13) || None || 17,694 || 81–76 |- style="background:#fbb" | 159 || September 25 || Cardinals || 1–4 || John Fulgham (10–6) || Dan Larson (1–1) || None || 16,163 || 81–77 |- style="background:#bfb" | 160 || September 26 || Cardinals || 11–5 || Steve Carlton (17–11) || Silvio Martínez (15–8) || None || 18,458 || 82–77 |- style="background:#bfb" | 161 || September 28 || @ Expos || 3–2 (11) || Ron Reed (13–8) || Woodie Fryman (3–6) || None || 40,303 || 83–77 |- style="background:#fbb" | 162 || September 29 || @ Expos || 2–3 || Elías Sosa (8–7) || Rawly Eastwick (3–6) || None || 50,332 || 83–78 |- style="background:#bfb" | 163 || September 30 || @ Expos || 2–0 || Steve Carlton' (18–11) || Steve Rogers (13–12) || None || 50,824 || 84–78 |- | style="text-align:left;" | The September