Background: Young adults and adolescents are rarely aware of the negative effects of caffeinated energy beverages. Aim of the work: To investigate the hazards of caffeinated energy drinks on the thyroid gland in albino rats by biochemical, histological, and immunohistochemical examinations, and examining the signs of the apoptosis/regeneration rate. Material and methods: 24 adult albino rats were classified into 3 groups; group 1 were kept on basal diet and distilled water, group 2 and group 3 were given energy drinks in 2 different doses for 14 days. Rats in group 2 were given a daily low dose of caffeinated energy drinks daily (10 mg/kg), while the group 3 of rats were given a daily high dose of caffeinated energy drinks (20 mg/kg). Finally, T3, T4 and TSH were measured, histopathology and immuno-histochemical study using ki-67 and caspase-3 were performed. Results: The mean free T3 and T4 in (groups 1, 2 and 3) showed statistically significant higher values. There was a significant difference regarding ki-67 in the 3 studied groups; the mean ki-67 score showed the highest value in group 3 followed by the control group and group 2 respectively, while there was a non-significant difference regarding caspase-3 in the 3 studied groups. Conclusion: Oral consumption of energy drinks was associated with significantly overexpression of ki-67 in thyroid gland suggesting a proliferative response to thyroid gland injury and significant increase in free T3 and T4 in group 2.