* Horst Tappert as Derrick
* Fritz Wepper as Harry Klein
* Edward Meeks as Mr. Jackson
* Barbara Rütting as Barbara Klein
* Michael Ande as Dr. Werner Jansen
* Karl-Michael Vogler as Dr. Georg Berger
* Marianne Hoppe as Frau Berger
* Willy Reichert as Herr Berger
Guest stars
* Hans Klering as Kommissar Lechner
* Karl-Heinz Vosgerau as Inspektor Brandl
* Heinz Drache as Oberinspektor Keller
* Harry Wüstenhagen as Kriminalrat Walter
* Eva-Ingeborg Scholz as Frau Walter
* Ingrid van Bergen as Gaby
* Peter Pasetti as Peter
* Doris Kunstmann as Doris
* Werner Hinz as Herr Hinz
* Hilde Hildebrand as Frau Hildebrand
* Peter Vogel as Herr Vogel
* Ingrid Andree as Frau Andree
* Peter Schiff as Herr Schiff
* Ingeborg Schöner as Frau Schöner
* Heinz Reincke as Herr Reincke
* Tilly Lauenstein as Frau Lauenstein