Nyandarua County (until 2010 Nyandarua District ) is a county in the Kenyan Central Province. The capital of the county is Ol Kalou. The County is located in the northwest of the province of Central, west of the Aberdare Range. Nyandarua County is divided into six divisions: Ndaragwa, North Kinangop, Ol Kalou, South Kinangop, Ol Joro Orok and Kipipiri.
The main economic activity in Nyandarua County is agriculture. Mainly are corn, beans, peas, potatoes, white and green cabbage, carrots, onions and tomatoes, as well as wheat, barley, Tanacetum and cut flowers. Livestock production is mainly focused on dairy cattle and merino sheep.
Nyandarua County has a road network of about 1000 km, with only 14 % of the roads are paved, 19 % are gravel roads. In the county there are ten post offices and eleven financial institutions. There are 36 public health facilities.