Forced to live in the Lodz ghetto he used his position in the statistics department to obtain the material needed to take photographs. By hiding his camera in his raincoat, Grossman was able to take secret photographs of scenes in the ghetto.
Grossman continued to take photographs after he was deported to the Konigs Wusterhausen labour camp. Mendel Grossman died while in the camp in 1945. After the war his hidden negatives were discovered and his work was published in the book, With a Camera in the Ghetto (1977).