The present study is to investigate the effects of myricetin on pubertal development and thyroid hormone concentrations in the male rat. The rats were exposed to 25 and 50 mg/kg/day of myricetin by gavage from post natal day (PND) 23 to 53. Preputial separation (PPS), organ weights and biochemical and hormone analysis were investigated. PPS was significantly delayed in low dose myricetin groups. Total serum thyroxine (T4) and, triiodothyronine (T3) levels increased in 25 mg/kg myricetin dose group but thyroid-stimulating hormone (TSH) level increased in 0.7 mu g/kg/day ethinyl estradiol dose groups. Myricetin exposure did not significantly change androgen dependent tissue weights; however myricetin exposure caused congestion, germinal cell debris and tubular atrophy in testis colloidal and tubular degeneration in thyroid gland were observed while there was germinal cell debris in epididymis. This study demonstrated that orally gavages myricetin caused adverse effects on male thyroid-gonadal axis during peripubertal period to pubertal period. (C) 2015 Published by Elsevier B.V.