ROS are important mediators of sperm function. Production of malondialdehyde (MDA), an end product of LPO, has been reported in spermatozoa. Ethnobotanical survey revealed [Anthocleista djalonensis A. Chev (Loganiaceae), Carpolobia lutea G. Don (Polygalaceae), Cassia sieberiana DC (Leguminosae), Chasmanthera dependens Hochst (Menispermaceae), Cissus populnea Guill and Perr (Vitaceae), Cnestis ferruginea DC (Connaraceae), Dioscorea cayenensis Lam. (Dioscoreaceae), Lecaniodiscus cupanioides Planch (Sapindaceae) and Microdermis keayana J. Leonard (Pandaceae)] as common medicinal plants used locally in South West Nigeria to boost libido, induce erection, increase sperm count and consequently male fertility. Inhibition of lipid peroxidation by these plant extracts as index of male fertility was assessed. MDA was assayed by thiobarbituric acid (TBA) reaction on lipid peroxidation in raw/cooked fish homogenates and measured as the amount of thiobarbituric acid reactive Sample (TBARS) in nmol mg-1 tissue. Extracts significantly inhibited extent of lipid peroxidation. A. djalonensis was most active while D. cayenensis was least active in both raw and cooked fish homogenates. TBARS activity/Concentration (R2 = 0.9533 for raw and R2 = 0.9739 for cooked). Thus these plants may be considered as cheap and readily available sources of treating sexual dysfunction in men.