Rădulescu was born in
Râmnicu Vâlcea in a family of merchants. After graduating from the Nicolae Bălcescu High School (now known as
Alexandru Lahovari National College) in Râmnicu Vâlcea, he had to make a choice between a career as a professional sportsman (boxing) and acting. He was even awarded a golden star at an amateur boxing championship.
In 1956, he won first prize for interpreting "Steaguri pe turnuri" (he played the bandit Rijikov) at a contest dedicated to young actors. He was then scouted by Sică Alexandrescu which meant the beginning of Rădulescu's acting career. Rădulescu befriended
Ion Cojar and
Liviu Ciulei; with the later he collaborated for the role of Farfuridi in O scrisoare pierdută, where he had exceptional actors as colleagues:
Rodica Tapalagă [
ro],
Petre Gheorghiu [
ro],
Ștefan Bănică,
Mircea Diaconu,
Octavian Cotescu,
Aurel Cioranu [
ro], and Ciulei himself. Liviu Ciulei called Dem Rădulescu "a genius of acting".
^Decretul nr. 1017 din 6 noiembrie 1967 al Consiliului de Stat al Republicii Socialiste România privind conferirea de ordine și medalii unor actori, regizori, pictori scenografi și tehnicieni de scenă, publicat în Buletinul Oficial nr. 96 din 7 noiembrie 1967.