Born and raised in Zürich-Oerlikon, Canton of Zürich in Switzerland, to Elise née Boller and Johannes Rudolf,[1] Margrit Rosa Sandmeier dreamed of a circus career.

Her parents forced her to make an apprenticeship as a photo lab assistant, but she secretly took acting classes and singing lessons.

Engagements at the Corso Theater Zürich and on occasion of the Swiss National Exhibition Landi'39 at Zürichhorn as Mäiti in the Swiss-German play "Steibruch", brought her artistic breakthrough.

In the Swiss television she appeared in 25 episodes of Ein Fall für Mändli alongside Ruedi Walter and Inigo Gallo between 1973 and 1975.

Beside the stage and television and film, from 1970 to 1982 she participated in a number of children's fairy tales and musicals directed by Jörg Schneider.

"D'Mutter wott nur s'Bescht" and "Potz Millione", that became in 1980 a great success, touring with Rainer, Walter, Gallo and Ines Torelli.

[1] Margrit Rainer and Ruedi Walter often was rumored to be a couple; indeed in the early days of their joint cooperation, but in 1959 the private paths of the film and stage partner separated.