Aleksey Batalov

as Dmitri Gusev

Innokentiy Smoktunovskiy

as Ilya Kulikov

Tatyana Lavrova

as Lyolya

Mikhail Kozakov

as Valery Ivanovich

Nikolai Plotnikov

as Professor Sintsov

Sergei Blinnikov

as Butov

Evgeniy Evstigneev

as Nikolai Ivanovich

Valentin Nikulin

as young physicist