Idiopathic  oligoathenoteratozoospermia  (iOAT)  is a  common  finding in  the evaluation of male infertility. Oxidative stress (OS) may underlie its pathology. Tamoxifen and L-carnitine are used to treat idiopathic male infertility. The aim of this work was to detect the efficacy of tamoxifen and L-carnitine on sperm parameters,  sperm  ultrastructure   and  seminal  OS  in  iOAT  patients.  Sixty patients  were recruited  for this study and  divided into  three groups; the 1st was treated  with  tamoxifen, 2nd  with  L-carnitine  and  3rd  with  both  drugs. Semen analysis, malondialdehye (MDA) level and transmission electron microscopy were performed before and after three months treatment. The first group  showed significant improvement  in  MDA levels, sperm  concentration, sperm morphology, ultrastructural  head, acrosomal and mitochondrial anoma- lies (P < 0.01). Other parameters were not  significantly improved. In the 2nd group, significant improvements in MDA, sperm motility, sperm morphology, ultrastructural  mitochondrial  and tail anomalies were detected (P < 0.01). No significant improvement in the other parameters. Third group showed improvement  in MDA, all semen parameters and all ultrastructural  anomalies (P < 0.01). In conclusion, tamoxifen and L-carnitine are effective in improving seminal OS, semen parameters and sperm ultrastructure. Combination  of both drugs is superior to monotherapy.