A novel palladium(0)-catalyzed cycloisomerization of enallenes has been developed. This reaction, catalyzed by [Pd(dba)2] (dba=dibenzylideneacetone) in acetic acid, results in the formation of cyclopentene derivatives and [n.3.0]bicyclic systems (n=3, 4) in good to high yields. The carbon-carbon bond-forming step is highly stereoselective to give cis-fused bicyclic systems. The presence of acetic acid as solvent and dba as ligand for palladium(0) turned out to be essential for the reaction in order to provide good reactivity and regioselectivity.