Thrombophilia as a cause of unexplained infertility is still questionable, though some studies suggested thrombophilia as a cause of unexplained infertility. Our results suggest that thrombophilia should be considered as an important cause of unexplained infertility and recommend using D dimer as a screening test. This test represents a speed method to diagnose thrombophilia in these subjects and has a good cost/benefit ratio.We recommend further studies on cases with elevated D dimer levels to detecttheexacttypeofthrombophiliawhichprevail. Thromboprophylaxis could be considered as an empirical treatment for these cases with unexplained infertility and suspected thrombophilia before proceeding to other treatment modalities as I.V.F. and also to improve its results, however, large scale study is highly recommended.