It is predicted that metal nanostructures can have a magnetic plasmon resonance (MPR) in the optical spectral range. Similarly to the known electrical surface plasmon resonance (SPR), the MPR depends only on metal properties and geometry of the system, rather than on the wavelength, and it can occur in structures much smaller in size than the optical wavelength. The MPR can have as large optical cross-section as the SPR so that nanostructures supporting the two resonances can provide a strong coupling to both field components of light, electrical and magnetic. Above the resonance, the magnetic plasmon polarizability may acquire negative values making possible to use this phenomena for developing left-handed materials in the optic range.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.