 Jan TřískaJan Svozil | Jan Svozil |
| JJana HliňákováNot listed | Not listed |
| JJaroslav RavaStanislav Hradecký | Stanislav Hradecký |
 Jana HlaváčkováVlasta Martínková | Vlasta Martínková |
 Gabriela WilhelmováHana | Hana |
 Zdena HerfortováEva Svozilová | Eva Svozilová |
 Oldřich VykypělROH chairman | ROH chairman |
| OOldřich SlavíkJaroslav Stehlík (uncredited) | Jaroslav Stehlík (uncredited) |
| JJiří HanákMiroslav Janoušek (uncredited) | Miroslav Janoušek (uncredited) |
 Vilém PfeifferBartoněk (uncredited) | Bartoněk (uncredited) |
| JJiří DušekZdražil (uncredited) | Zdražil (uncredited) |
 Milan PásekInstitute director (uncredited) | Institute director (uncredited) |
| KKarel AdamDepartment manager (uncredited) | Department manager (uncredited) |
| HHelena TrýbováScientist (uncredited) | Scientist (uncredited) |
| VVladimír PavlarDoc. Rozehnal (uncredited) | Doc. Rozehnal (uncredited) |
| BBohumil SlezáčekProfessor (uncredited) | Professor (uncredited) |
| AArnošt NavrátilDoctor (uncredited) | Doctor (uncredited) |
| SSylvie NitrováNurse (uncredited) | Nurse (uncredited) |
| MMarcela DürrováLaboratory assistant (uncredited) | Laboratory assistant (uncredited) |
 Miroslav DonutilAssistant (uncredited) | Assistant (uncredited) |
| MMilan KročilAssistant (uncredited) | Assistant (uncredited) |
 Zdeněk MaryškaAssistant (uncredited) | Assistant (uncredited) |
| ZZdeněk DryšlHouseman (uncredited) | Houseman (uncredited) |
 Jana GazdíkováSecretary (uncredited) | Secretary (uncredited) |
| BBlažena RýznarováOfficial (uncredited) | Official (uncredited) |
| MMarkéta RauschgoldováCanteen assistant (uncredited) | Canteen assistant (uncredited) |