Over expression of tyrosinase can cause excessive production of melanin and lead to hyper pigmentation disorders, including melasma and freckles. Recently, agents obtained from plants are being used as alternative medicines to down regulate tyrosinase synthesis and decrease melanin production. Ayurveda and various traditional systems of medicines claim that foeniculum vulgare (Umbelliferacacae ) is also highly recommended for diabetes, bronchitis and chronic cough, for the treatment of kidney stones, and is considered to have diuretic, stomachic and galactogogue properties. The anti melanogenesis activity and molecular biological mechanism underlying the activity of the methanolic extract of Foeniculum vulgare have not been investigated to date. This study aimed to determine the effect on melanin production and biological mechanisms underlying anti melanogenesis of methanolic extract of Foeniculum vulgare inB16 cells. Confluent monolayer of B16 cells were taken α-MSH was prepared, Reverse transcriptase PCR was carried out and the PCR product was examined using agarose gel electrophoresis. RT-PCR (Reverse Transcriptase) was carried out to study the expression of MITF and TRP-2. The results showed a significant time dependent decrease gradually, especially the decrease was observed at 72 hrs. The control showed no change with the incubation time. The result confirms that the sample down- regulated the gene expression.