When by Showaddywaddy first appeared on the Israeli foreign-music chart on 10 Apr 1977, entering at #21. It peaked at #3 on 1 May 1977. In total it spent 9 weeks on the chart, last charting on 12 Jun 1977.
| Wk | Date | Pos |
|---|---|---|
| 1 | 10 Apr 1977 | 21 |
| 2 | 17 Apr 1977 | 12 |
| 3 | 24 Apr 1977 | 6 |
| 4 | 1 May 1977 | 3 |
| 5 | 8 May 1977 | 3 |
| 6 | 15 May 1977 | 9 |
| 7 | 22 May 1977 | 14 |
| 8 | 29 May 1977 | 19 |
| 9 | 5 Jun 1977 | 28 |