<p>The current study design to assess the dose-response effect of administering an aqueous extract of guava leaves on the microstructure of the testicles due to the growing use of this plant in complementary and alternative medicine practice.&nbsp;Twenty-four male albino Wistar rats with an average body weight of 160 g apportion to four groups (n=6 each). Group, I served as the control and received distilled water; group II gave a lower dose of 500 mg/kg body weight of guava leaf extract; group III received a medium dose of 750 mg/kg; while group IV administer a higher amount of 1000 mg/kg per day. Treatments were given once daily by gavage and lasted for 14 days, while the stock solution prepares by dissolving 50 g of the extract in 30 ml of water. The cervical dislocation method used to euthanize the rats, dissect the abdominopelvic region to obtain tissue specimens from the testes for histological processing.&nbsp;The outcome exhibited the extract to cause moderate to severe (dose-dependent) morphological alterations with the seminiferous tubules' fibrotic appearance, strict spermatogenic arrest, and necrosis of both the interstitial cells of Leydig and the Sertoli cells.&nbsp;The ingestion of guava leaves at the investigated concentration and doses is harmful to the testicle, the primary reproductive organ in males. It should therefore be consumed with caution when being used primarily in folklore-traditional medicine.</p>