on 7 January 1593, Johann married Dorothea Maria of Anhalt. They had twelve children in just twelve years:

# John Ernest I, Duke of Saxe-Weimar (b. Altenburg, 21 February 1594 - d. Sankt Martin, Hungary, 6 December 1626).
# Christian William (b. and d. Altenburg, 6 April 1595) died at birth.
# Frederick (b. Altenburg, 1 March 1596 - killed in battle,