The results of this study has revealed a significant increase in I(131) uptake of cultivated thyroid gland in the media containing petroleum ether extract of Commiphora mukul. Besides, T(3) resin uptake, protein bound iodine as well as free thyroxine index in the media are also observed to be significantly (P 0.001) increased. When explants are cultivated in the media containing melatonin, there is significant depression in thyroid I(131) uptake and media T(3) resin uptake, protein bound iodine as well as free thyroxine index. Further, the inhibitory action of melatonin has been antagonized when similar explants are cultivated in the media containing melatonin and P.E. extract of c. mukul together thus, C. mukul may be useful in the management of hypothyroidism and its associated disorders like, hypercholesterolemia, hyperlipidemia, atherosclerosis etc.