An ethnobotanical survey was conducted from May 2009 to September 2011 in the villages adjacent to the Ovan Lake in Alamut region, 75km northeast of Qazvin city, Qazvin province, Iran. The survey was aimed to identify the indigenous knowledge about the traditional and medicinal usages of the plants growing in the region. The general pharmacopoeia among the Ovan’s peoples was examined and recorded by means of standardized interviews, especially with housewives and elder lies assumed to have a rich knowledge about the plants. A total of 129 plant species, belonging to 40 families and103genera were found to be extensively used by local inhabitants for various purposes such as fuel, furniture, fodder, making baskets and mats, brushing teeth, vegetables, edible fruits and in the last resort medicinal uses. The documented medicinal plants were applied to treat a wide spectrum of syndrome and diseases, from common cold to cancer, many of which were justified by recent scientific surveys.