Dittmer is an unincorporated community in western Jefferson County, Missouri, United States. It is located approximately 14 miles northwest of Hillsboro on Route 30. The community is shown on an early railroad map, published in 1891, as "Dittmer's Store."
A post office called Dittmer's Store was established in 1870, and the name was changed to Dittmer in 1899. William Dittmer, an early postmaster, gave the community his last name.
The settlement is home to the Vianney Renewal Center, a treatment center for Catholic clergy with sexual or other disorders.