Addiction is a major problem confronting the whole world today. Disruption of interpersonal relationships, economic loss, and crimes against property are frequent consequences. Harm to the individual himself extends to all physiological systems, Aim and objectives: The aim of this study is to evaluate the effect of diacetylmorphine addiction on sperm ultrastructral morphology by electron microscope in patient attending Benha Psychiatric Hospital, Subjects and methods: An observational cross-sectional study was done including 50 addict patients who were admitted in addiction section in Benha psychiatry hospital. Patient who were addict on diacetylmorphine; age> 20 years old for at least one year were enrolled in this study. The duration of the study ranges from 6 to 12 months, Results: The present study shows that Acrosome present was 84.1 ± 12.4 , Nucleus Normal shape was 46.1 ± 6.8, Nucleus Normal shape was 46.1 ± 6.8 ,Chromatin was 70.1 ± 1.7 ,Cytoplasmic residue absent was 74.6 ± 5.7,Mitochondria Normal shape was 85.2 ± 8.5 ,Normal helix was 83.1 ± 4.3 , Axoneme Normal pattern was 56.7 ± 8.4 ,Normal arms was 57.3 ± 6.8,Normal shape was 90.4 ± 4.1 ,Accessory fiber normal was 77.1 ± 11.6 ,Fibrous sheath normal 99.7 ± 15.3 Plasma membrane normal was 90.2 ± 12.3, Conclusion: Heroin consumption affects sperm maturities such as histone-to-protamine ratio and impair semen profile in general and particularly sperm morphology and motility. Heroin may be considered as one of the idiopathic male infertility reasons.