Background: Cyproconazole (CPZ) is a triazole fungicide used to protect crops against a variety of fungal diseases. Objective: This investigation aimed to evaluate the probable protective benefits of fennel oil, a natural oil extracted from the plant Foeniculum Vulgare, against CPZ-induced adrenal gland injury in rats. Methods: Sixty male rats were allocated into: control, fennel oil, CPZ-low dose, CPZ-high dose, CPZ-low dose + fennel oil, and CPZ-high dose + fennel oil. After 15 days of daily treatment, serum levels of adrenocorticotropic hormone (ACTH), cortisol, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC), and free cholesterol (FC) were estimated. The adrenal gland tissues were also investigated to assess the amount of reduced glutathione (GSH), malondialdehyde (MDA), the efficacy of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), along with evaluating the status of DNA fragmentation using the Comet assay. Results: CPZ substantially induced damage in the adrenal gland, as evidenced by elevated serum levels of ACTH, TC, FC, and LDL-c as well as reduced serum levels of cortisol and HDL-c. Also, high levels of MDA, decreased GSH levels, and diminished activities of SOD, CAT, and GPx in adrenal gland tissues in CPZ-treated groups. Furthermore, CPZ caused DNA damage in adrenal gland cells. Fennel oil co-treatment reversed CPZ hazardous effects on the biochemical parameters and DNA damage. Conclusion: This study claimed that fennel oil co-treatment could ameliorate CPZ-induced adrenal gland injury in male rats.