Abstract: The methyl esters from the extracts of three green algae (Enteromorpha intestinales, Ulva rigida and Ulva fasciata) and one of red alga Hypnea cornuta were qualitatively and quantitatively analysed through GLC technique. A wide variety of saturated and unsaturated fatty acids were detected. Fourteen fatty acids in the four specimens of seaweeds registered namely, capric, lauric, tridecanoic, myristic, myristoleic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, arachidonic and eicosapentanoic. The total sum of the recorded fatty acids increase in the order: Enteromorpha intestinales < Ulva rigida < Ulva fasciata < Hypnea cornuta, with percentage; 71.77, 73.05, 74.05 and 88.17%, respectively. Hypnea cornuta was characterized by the presence of arachidonic acid (Omega-6 C20:4; 1.091%) and eicosapentanoic acid (Omega-3 C20:5; 6.264%), while they disappeared from the other selected green algae specimens. The arachidic was existed only in Ulva rigida (1.10%) and Hypnea cornuta (0.88%). Palmitic content showed its maximum value 25.87% in Enteromorpha intestinales. Saturated fatty acids capric, lauric, tridecanoic and unsaturated myristoleic recorded their highest concentrations in Ulva rigida, with percentages 3.72, 6.57, 8.57 and 4.5%, respectively. Ulva fasciata characterized by containing the highest levels of the most biologically active fatty acids Omega-9 (oleic C18:1; 8.03%), Omega-6 (linoleic acid C18:2; 12.41%) and Omega-3 (linolenic acid C18:3; 3.19%).