Among algae, green algae contribute to the creation of a biological balance in seas and oceans, taking part to the water purification processes, carbon fixation and serving as feed for marine fauna. For mankind, they are important in food production, in medical fields, dietetics and cosmetics. Ulva Lactuca and Ulva Rigida are the most important green algae from the mean coastal area of the Black Sea. Their industrial capitalization is still poor; no theoretical studies have yet been performed. In this approach, the present work outlines in a detailed manner the active principles of these algae that, due to the recent established ecological equilibrium, represent nowadays a plentiful biomass.