Background: Tarantula cubensis (theranekron), obtained from the poison of Cuban Tarantula, is a homeopathic drug frequently used in animal health. Objectives: The effect of theranekron on reproductive parameters in male animals is unknown. In this study, the effect of theranekron on male reproductive parameters was investigated. Methods: Three different groups of rats were created: control (n=8) (no application), theranekron I (n=8) (subcuteneous injection of 0.3 mg/kg on days 0, 5, and 10), and theranekron II (n=8) (subcuteneous injection of 0.3 mg/kg on days 0, 5, and 10). Control and theranekron I groups were sacrificed at the end of the 4 weeks, and the theranekron II group was sacrificed at the end of the 6 weeks. Sperm motility, density, abnormal rate, DNA damage, and testicular histopathology were examined. Results: No statistical difference was observed in the parameters examined between the study groups (P>0.05). It was determined that the theranekron did not change sperm motility, density and spermatozoa ratio, also no histopathological changes, and sperm DNA damage. Conclusion: There is no harm in using theranekron in male animals during the breeding and nonbreeding seasons.