On Friday, February 21, 1868, he married Elisabeth Sophie Wilhelmine Frederica Adolphine Knaack who was born November 5, 1841 in Mamerow, Germany. She was baptized in the village church in Klaber on November 14,1841.

August and Rika (Knaack) Heiden had eight children including Heinrich "Henry" (1866-1922), Ernst "Ernest" (1868-1950) and Meta (1870-1873 who were born in Germany. William Carl (1874-1967), Bertha (1876-1877), Herman (1876-1957), Lena (Koster 1881-1973) and John (1884-1959) were born in America. Bertha and Herman were fraternal twins. Meta died shortly after the family emigrated to America in 1873.