| Jenny Kastein | |
| Birth Date: | 24 January 1913 |
| Birth Place: | Amsterdam, the Netherlands |
| Death Date: | 20 October 2000 (aged 87) |
| Death Place: | Zwolle, the Netherlands |
| Sport: | Swimming |
| Club: | HDZ, Amsterdam |
| Show-Medals: | yes |
Jeannette "Jenny" Hermine Kastein (24 January 1913 - 20 October 2000) was a Dutch breaststroke swimmer. She won a silver medal in the 200 m breaststroke at the 1931 European Championships, behind Cecelia Wolstenholme. Next year she set four world records in the 400 m and 500 m breastroke (unofficial events), but could not compete in the Olympics due to the overall financial problems related to the Great Depression. She won the national titles in the 200 m in 1933, 1935 and 1936, yet her performance declined, and at the 1936 Summer Olympics she finished in a mere seventh place.
In 1942, Kastein married Evert Heleonardus Scheijde, a physician; they had two sons.