We present a check-list of the seaweeds for Venice lagoon, based on literature and recent records. At present the total number of taxa is 277, including 71 Chlorophyceae s.l. (25.6%), 148 Rhodophyceae (53.4%), 56 Phaeophyceae (20.2%) and 2 Chrysophyceae (0.7%). Using present day taxonomy, the number of taxa is about double that in previous lists. Since 1983, there have been 92 (ca. 33%) new records for Venice littoral zone. Of these, 19 (ca. 21%) are first records for the Mediterranean Sea, and many are alien taxa that seriously compete with the growth of indigenous species. The number of taxa that have disappeared from the lagoon, or have not been found in the recent years, is 96.