Diedenshausen is a small village, since 1975 a constituent community of Bad Berleburg in Siegen-Wittgenstein district and Arnsberg region in North Rhine-Westphalia in the Federal Republic of Germany. It is located on the east side of the heavily forested Rothaargebirge (Red-haired Mountains), immediately on the border with Hesse. A few houses lie to the east of the Elsoff creek which forms the state border, and they are technically in Hesse.