Hjartdøla is a river in Hjartdal municipality in Telemark, Norway. The 26 km long river is part of the Skien watershed. The river is formed at the confluence of the river Bjordøla and some smaller rivers coming from the lakes Skjesvatnet and Breidvatnet, about 5 km north of the village of Hjartdal. From here, it runs through the village of Hjartdal, then through the lake Hjartsjåvatnet, and through the village of Sauland. At Sauland, the river meets the river Skogsåa and after this confluence, the two rivers form the river Heddøla which then continues on to Heddal and the lake Heddalsvatnet.