34 spp. were recorded at running and stagnant waters in the Serpa region. The finding of several spp. is noteworthy: Gomphus graslinii (Ramb.), Paragomphus genei (Sel.), Onychogomphus costae Sel., Aeshna isosceles (Müll.), Libellula depressa L., L. quadrimaculata L., Orthetrum nitidinerve (Sel.) and Sympetrum sanguineum (Müll.). Orthetrum trinacria (Sel.) is for the first time reported from Portugal. Phonological, reproductional and other biological facts are provided, and some aspects of ecological preferences are discussed.