To find new products reducing free radical damage is very important research area in recent pharmaceutical investigations. Considering this information, different marine sponges distributed in Mediterranean coasts of Turkey were screened for their antioxidant capacity. Methanolic extracts of eleven species from six different localities were investigated for their 2,2-diphenyl-1-picrylhydrazil (DPPH), nitric oxide (NO) and superoxide (SO) radical scavenging activities. Dose dependent radical scavenging activity was observed and the results were found to be comparable to that of known antioxidative compounds, ascorbic acid, quercetin and BHA. The most significant scavenging activity was determined for the methanolic extracts of Dysidea avara, Axinella cannabina, Axinella damicornis, Agelas oroides and Ircinia fasciculata. In addition, localities of the sponges were found to be effective for the potency of their activities.