required for the spermatozoa (Peterson and Freund -1971). The role of lipids in supplying the needed energy through oxidative processes still remains obscure. The aim of the present work was to demonstrate this role by determining the level of non-esterified fatty acids, triglycerides, fructose and lipoprotein lipase enzyme activity, immediately and 2 hours after liquifaction in the semen of normozoospermic, oligozoospermic and azoospermic men. Material and MethodsThe present study was carried out on the semen of 37 males. 20 of them were attending the male sterility clinic of Cairo university Hospital complaining of primary sterility. The remaining were fertile, had no relevant complaint and were selected from the Dermatology clinic. These males were divided into three groups: Group I: Control group composed of 17 fertile and clinically free males. Group 11: This group included 10 patients complaining of primary sterility. Members of this group were oligoasthenozoospermic and all were clinically free. Group 111: This group was composed of 10 patients complaining of primary sterility, their semen analysis showed azoospermia. Clinically, all of them were free. From the three groups semen was obtained by masturbation, left to liquify and a sample was examined immediately for: fructose (Karvonen and Malm -1975); non esterified fatty acids (NEFA) (Duncombe -1964); triglycerides (Lloyd and Goldrich -1968) and lipase (Kits produced by *Biomerieux Company). Two hours later, the rest of the ejaculate which was kept at room temperature was subjected to the same estimations. Resultsmediately and two hours after liquefaction are shown in the table. It is clear from the table that:The level of non esterified fatty acids (NEFA), triglycerides and fructose in semen im-