Semaya and Sikasur sands, which located in Pemalang Regency, is used by the people as a mixture of concrete material. The mud contained in Semaya and Sikasur sand is different. This research is an experimental research to find out the mud content of sand in sand to concrete compressive strength. To find out the compressive strength of concrete it is used cylindrical specimens whit a diameter of 15 cm x 30 cm with the use of variations Semaya and Sikasur sands with a compressive strength testing plan of 19,3 MPa at the concrete age of 7 days. The results showed that Semaya sand had a mud contain of 2,53%, while Sikasur sand had a mud contain of 3,1%.