Objective To illustrate the importance of treatment duration with intramuscular testosterone undecanoate (Nebido®) for the final spermatogenesis recovery after treatment cessation. Also, to show a subsequent poor efficacy of the selective estrogen receptor modulator (SERM) clomiphene citrate (CC) in treating steroid-induced azoospermia following Nebido® cessation and describe that initial oligozoospermia, existing before starting Nebido®, largely contributes to that treatment outcome. Methodology Setting: Department of Human Reproduction and Department of Endocrinology, Clinical Hospital Center Rijeka, Rijeka, and Department of Endocrinology, Clinical Hospital Center Sestre milosrdnice, Zagreb, Croatia.A male patient having been diagnosed with primary hypogonadotropic hypogonadism, oligozoospermia and low testosterone (T) level, was treated with intramuscular testosterone undecanoate (TU) depot 1 g (Nebido®) to prevent further progression of testosterone deficiency symptoms (low mood, energy and concentration, fatigue, muscle weakness).Stopping Nebido® and treatment with CC 50 mg per day 5 days per week for 3-6 month to recover spermatogenesis.T levels and semen analyses. Results Semen analyses did not return to values before taking Nebido® 1 year after cessation nor after 3 months of treatment with CC. Values of T, follicle stimulating hormone (FSH) and luteinizing hormone (LH) dropped even more than before starting Nebido®, after 1 year of cessation. Conclusions Here we describe a case of initially idiopathic gonadal failure with subsequent secondary gonadal failure and infertility resulting from testosterone replacement therapy (TRT) treatment, and poor spermatogenesis recovery outcome of CC used post Nebido® cessation.