The purpose of this research was to investigate the acute effects of Tarantula cubensis extract (Theranekron, 1:100/D2, Richter Pharma, Austria) on some serum enzymes and trace elements, and the cardiovascular system in sheep. Seven sheep (age 6 months, 35±10 kg) were used in this study. Theranekron was applied in 6 ml doses subcutaneously. It was determined that in the serum Urea, Creatinin, ALT, ALP, G-GT, LDH, Ca and P levels were increased and T. protein, Mg, Cu, Fe, Zn and Se levels were decreased. The important results obtained after the treatment with Theranekron on cardiovascular system were blood pressure increases and some morphological changes in ECG. We concluded the Theranekron treatment can cause adverse effects in sheep and further investigation of the efficacy of Theranekron treatment is warranted.