Владимир Гардин
— Professor Shakhrov
Николай Кутузов
— Kuznetsov
M. Tulupov
— Professor Yaroshevskiy
Хаким Давлетбеков
— Khakim
Евгения Пырялова
— Zhenya Maltseva
Борис Азаров
— Zaretskiy
Kheyhana Tastakhova
— Young kazakh woman
Сергей Голубев
— Telegraph operator
V. Zakharov
— Guryev, student (uncredited)
Николай Мичурин
— Factory worker (uncredited)
Владимир Ромашков
— Scientist (uncredited)
Vladimir Stukachenko
— Factory worker (uncredited)
Владимир Чобур
— Komsomol member (uncredited)