His breakthrough role was Imre Madách's Moses, which he had played for 22 years, more than 700 times.

Sinkovits became a member of the Hungarian Theatre and Film Association Revolutionary Committee on 30 October.

[citation needed] After the revolution was crushed, Sinkovits was banned from acting for a half year for his activities, and his membership in the National Theatre was terminated.

He played the leading role in a number of films and television series, and was also involved in dubbing and narration.

[3] At 4 May 1991 reburial ceremony of Jozsef Cardinal Mindszenty in Esztergom, Sinkovits delivered a powerful rendition of Hungarian poet Mihály Vörösmarty's poem Szózat before the 50,000 mourners in attendance.