Matrix-assisted laser desorption of proteins with the 355 nm frequency-tripled output of a neodymium:yttrium-aluminium-garnet laser has been demonstrated. In order to produce desorption at this wavelength, the cinnamic acid derivatives ferulic, caffeic and sinapinic acids have been employed as matrices. Excellent sensitivity (routinely one pmol of protein) and good mass resolution (m/delta m 400, Full width at half maximum) have been obtained by this new method. Ultraviolet photo-spectrometry of the cinnamic acid derivative matrices suggests strongly that they can be used as protein laser-desorption matrices at any wavelength between 260 nm and 360 nm, allowing the development of laser-desorption mass spectrometers based on nitrogen or excimer lasers.