| Roles | Non-starter | |
|---|---|---|
| Sex | Male | |
| Full name | Dethloff•Siem | |
| Used name | Dethloff•Siem | |
| Born | 20 January 1905 in Amsterdam, Noord-Holland |  NED |
| Died | 14 November 1973 (aged 68 years 9 months 25 days) | |
| NOC | Netherlands | NED |
| Games | Discipline (Sport) / Event | NOC / Team | Pos | Medal | As | |
|---|---|---|---|---|---|---|
| 1948 Summer Olympics | Equestrian Jumping (Equestrian) | NED |
Dethloff Siem | |||
| Individual, Open (Olympic) | ||||||
| Team, Open (Olympic) | Netherlands |
