Seaweeds are naturally rich with biological active metabolites that could be promising to be used in the biological control. The present study was conducted to evaluate the antifungal potentiality of metabolites extracted from Ulva fasciata, Ulva lactuca and Cladophora sericea; against Macrophomina phaseolina (Tassi) Goid. and Fusarium oxysporum Schltdl. Four organic solvents hexane, chloroform, acetone and methanol were used for extraction of seaweeds metabolites to assay their biological efficiency on mycelium growth reduction of two candidate soil borne fungal pathogens on potato dextrose agar medium. The highest percentage of F. oxysporum and M. phaseolina growth reduction was observed by acetone extract of U. fasciata and methanol extract of C. sericea. The highest inhibition against M. phaseolina reached up to 28.97% by U. fasciata acetone extract and 24.77% by C. sericea methanol extract. The highest percentage of mycelial growth inhibition of F. oxysporum was observed by U. fasciata acetone extract (23.58%) and C. sericea methanol extract (17.01%). Analysis of acetone extract of U. fasciata by gas chromatography mass spectrophotometer GC/MS revealed the presence of some organic compounds with antifungal properties such as Phenol, 2,2'-methylenebis[6-(1,1-dimethylethyl)-4-methyl-, Di-n-octyl phthalate, 1,2-Benzenedicarboxylic acid, diisodecyl ester, Didecyl phthalate, Phthalic acid, bis (7-methyloctyl) ester, gamma Sitosterol, Cholest-5-en-3-ol, 24-propylidene-, (3. beta.) and Cyclononasiloxane, octadecamethyl-. The results suggest that the studied algal species can be used as potential bio-agent source in biological control of soil borne phytopathogenic fungi.