The chemical investigation of the Mediterranean ascidian Clavelina phlegraea has led to the isolation of six new 2-amino-3-alkanol derivatives, clavaminols A-F (1-6). Their stereostructures were established by analysis of spectroscopic data and chemical conversion. Clavaminols A, B, C, and F were tested for their cytotoxic and pro-apoptotic properties and clavaminol A was shown to be the more potent cytotoxic compound of this series inducing cell death through activation of the apoptotic machinery.