Sepioteuthis lessoniana Lesson, 1830, represents the most common species of squids in the Red Sea. It was chosen for a detailed study of the macro- and microscopic anatomy of its male reproductive system with special reference to the structure of its spermatophores and the method of their formation.The male reproductive system is differentiated into a single testis and a gonoduct which consists of a vas deferens, a complex spermatophoric organ, a spermatophoric duct and a spermatophoric sac that ends with a muscular conducting tube. The testis is formed of a large number of closely compact seminiferous tubules containing different stages of spermatogenesis. The spermatophoric organ is composed of six glands: mucilagenous I & n, ejaculatory appartaus, middle and outer tunic and accessory gland with its appendix. The structure of each of these glands was demonstrated and discussed.The spermatophore of S. lessoniana is a minute structure that consists of a spermatophoric cord and an ejaculatory apparatus connected together through the connective region. The structure of different parts of the spermatophore and the method of their formation were studied and discussed.