| Title, Format | Label | Cat# | Country | Year | |
|---|---|---|---|---|---|
| Serious (12") | 21 Records | 2.148 | Netherlands | 1986 | |
| Serious (Delirious Mix) (12") | Portrait | 650744 8 | UK | 1986 | |
| Serious (Extended Remix) (12") | Portrait | 650744 6 | UK | 1986 | |
| Serious (Extended Remix) (12", W/Lbl) | Portrait | 650744 6 | UK | 1986 | |
| Serious (12") | 21 Records | 0-96794 | US | 1986 | |
| Serious (12") | 21 Records | 12-96794 | Canada | 1986 | |
| Serious (12", Promo) | 21 Records | DMD 980 | US | 1986 | |
| Serious (7") | 21 Records | 7-99497 | Canada | 1986 | |
| Serious (7") | 21 Records | 7-99497 | US | 1986 | |
| Serious (7", Single) | 21 Records | 21 048 | Netherlands | 1986 | |
| Serious (Special Extended U.S. Mix) (12") | TSR Music GmbH | TSR 20.05.01.01 | Germany | 1987 | |
| Serious (7") | Portrait | 650744 7 | UK | 1987 | |
| Serious (7", Single) | Portrait | PRT 650744 7 | Netherlands | 1987 | |
| Serious (12") | TSR Music GmbH | TSR 520102 | US |