| Roles | Competed in Olympic Games | |
|---|---|---|
| Sex | Female | |
| Full name | Margretta "Gretta"•Kok (-Mevissen) | |
| Used name | Gretta•Kok | |
| Born | 16 October 1944 in Amsterdam, Noord-Holland |  NED |
| Measurements | 176 cm / 64 kg | |
| Affiliations | HDZ — Amsterdam, Noord-Holland | NED |
| NOC | Netherlands | NED |
| Games | Discipline (Sport) / Event | NOC / Team | Pos | Medal | As | |
|---|---|---|---|---|---|---|
| 1960 Summer Olympics | Swimming (Aquatics) | NED |
Gretta Kok | |||
| 200 metres Breaststroke, Women (Olympic) | 5 | |||||
| 1964 Summer Olympics | Swimming (Aquatics) | NED |
Gretta Kok | |||
| 200 metres Breaststroke, Women (Olympic) | 15 |
