It is to assume, that all still living bearers of the name of Olnhausen are descendants of two brothers, Heinrich III. (1503 Vogt at Adolzfurt) and Jacob v. O. (since 1490 serving the city of Heilbronn as a mayor). At that time in late 15th Century the family was split up in the lines of Hohenlohe and Heilbronn.
The members of the stirps of Hohenlohe can be found from the beginning of the 16th until the beginning of the 19th Century in civil and military services for many more or less potent sovereigns in southwestern Germany and Austria. Members of the stirps of Heilbronn were in the 16th Century in the service of various imperial cities and the Duke of Württemberg. One branch was represented in the City Council of the city of Heilbronn at the end of the 16th Century. Many families are still to be found in various cities and towns in Württemberg, particularly in the small town Nordheim nearby the city of Heilbronn. Common ancestor of these families is Hans v. O. (1640-1699), who lived as a blacksmith and judge during the Thirty Years‘ War in Nordheim.
In the 19th Century there were several migrations to the United States and Ireland in the 20th Century also to Sweden and England. Due to the increased mobility in recent decades, nowadays bearers of the name of Olnhausen are found worldwide. In 2007 a phone book search resulted in 101 entries, with a focus in the Middle Neckar region with the districts of Heilbronn and Ludwigsburg.