Nils Rosén von Rosenstein was born near Gothenburg on Feb. 1, 1706 (old style). His father was Erich Rosenius, at the time an army chaplain, and his mother Anna Wekander, who came out of an exemplary family of clergymen. One of his brothers, Eberhard, became professor of medicine at Lund and was subsequently ennobled and took the name Rosenblad.
An anecdote on von Rosenstein's childhood, with which he used to entertain his friends, was that at the age of 4 he was stricken with plague and that he lay over twenty-four hours as dead. His mother, arranging his burial clothes, noticed signs of life and fainted.
In 1718, he attended the Gymnasium in Gothenburg, and two years later the Academy in Lund. His father intended him to enter the ministry, but from his early years he was inclined to the study of medicine. One of his early teachers in medicine