| Administrator: | Test and County Cricket Board |
| Cricket Format: | Limited overs cricket(40 overs per innings) |
| Tournament Format: | League |
| Champions: | Hampshire |
| Count: | 2 |
| Participants: | 17 |
| Matches: | 136 |
| Most Runs: | 637 Gordon Greenidge (Hampshire) |
| Most Wickets: | 27 Les Taylor (Leicestershire) |
| Previous Year: | 1977 |
| Previous Tournament: | 1977 John Player League |
| Next Year: | 1979 |
| Next Tournament: | 1979 John Player League |
The 1978 John Player League was the tenth competing of what was generally known as the Sunday League. The competition was won for the second time by Hampshire County Cricket Club.
| width=200 | Team | width=20 | Pld | width=20 | W | width=20 | T | width=20 | L | width=20 | N/R | width=20 | A | width=20 | Pts | width=60 | R/R |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hampshire (C) | 16 | 11 | 0 | 3 | 0 | 2 | 48 | 5.356 | |||||||||
| 16 | 11 | 0 | 3 | 0 | 2 | 48 | 4.580 | ||||||||||
| 16 | 11 | 0 | 3 | 0 | 2 | 48 | 4.266 | ||||||||||
| 16 | 10 | 0 | 5 | 0 | 1 | 42 | 4.567 | ||||||||||
| 16 | 9 | 0 | 6 | 0 | 1 | 38 | 4.632 | ||||||||||
| 16 | 7 | 0 | 6 | 0 | 3 | 34 | 4.633 | ||||||||||
| 16 | 7 | 0 | 7 | 0 | 2 | 32 | 4.807 | ||||||||||
| 16 | 6 | 0 | 7 | 1 | 2 | 30 | 4.569 | ||||||||||
| 16 | 6 | 0 | 7 | 0 | 3 | 30 | 4.038 | ||||||||||
| 16 | 6 | 0 | 8 | 0 | 2 | 28 | 4.501 | ||||||||||
| 16 | 6 | 0 | 8 | 1 | 1 | 28 | 4.144 | ||||||||||
| 16 | 6 | 0 | 8 | 1 | 1 | 28 | 4.090 | ||||||||||
| 16 | 5 | 0 | 8 | 1 | 2 | 26 | 4.543 | ||||||||||
| 16 | 4 | 0 | 7 | 0 | 5 | 26 | 4.515 | ||||||||||
| 16 | 5 | 0 | 9 | 0 | 2 | 24 | 4.299 | ||||||||||
| 16 | 4 | 0 | 11 | 0 | 1 | 18 | 4.438 | ||||||||||
| 16 | 3 | 0 | 11 | 0 | 2 | 16 | 4.257 | ||||||||||
| Team marked | |||||||||||||||||