| El secreto de la solterona | |
| Director: | Miguel M. Delgado |
| Producer: | Vicente Saisó Piquer |
| Based On: | Das Geheimnis der alten Mamsell by E. Marlitt |
| Starring: | Sara García |
| Cinematography: | Víctor Herrera |
| Editing: | Alfredo Rosas Priego |
| Runtime: | 105 minutes |
| Country: | Mexico |
| Language: | Spanish |
El secreto de la solterona (also known as The Secret of the Spinster or The Secret of the Old Maid) is a 1945 Mexican mystery romantic drama film directed and co-written by Miguel M. Delgado, based on an 1868 book of the same name by E. Marlitt.