To investigate the relationship between structure and biological activity of phenylpropanoids, we measured effects of phenylpropanoids on anti-oxidant and whitening activity, In DPPH radical scavenging activity, caffeic acid analogues showed the significant anti-oxidant activity. Although phenylpropanoids did not inhibit purified-tyrosinase activity, they significantly inhibited tyrosinase activity and melanin production in MSH-stimulated B16 melanoma cells. However, phenylpropanoids did not affect tyrosinase expression in MSH-stimulated B16 melanoma cells, which suggest that inhibition of MSH-induced melanin production was due to tyrosinase inhibition mediated via other signal pathways but not expression of tyrosinase. Phenylpropanoids also significantly inhibited both hyaluronidase and elastase activity, suggesting that phenylpropanoids may be used as whitening, hydration and anti-wrinkling agents. Hydroxyl residue of aromatic ring in phenylpropanoids plays an important role in anti-oxidant and whitening activity.