In addition to the known sodium 3,7,11,15-tetramethylhexadeca-1,19-diyl sulfate (4), the BuOH extract of the Mediterranean tunicate Sidnyum turbinatum was shown to contain four new metabolites: 1-heptadecanyl sulfate (1), 1-octadecanyl sulfate (2), sodium (2S)-2,6,10,14-tetramethylpentadeca-1,18-diyl sulfate (3), and 1-hexyl sulfate (5). Their structures were determined by spectroscopic and chemical methods. Compounds 1-5 exhibited in vitro antiproliferative activity estimated on the WEHI 164 cell line.