The polymerization of L-lactide was catalysed with Sn(II)2-ethylhexanoate (SnOct(2)) in the presence or absence of benzyl alcohol. The molecular weights parallel the lactide/benzyl alcohol ratio, but never the lactide/Sn ratio. H-1 n.m.r. spectroscopy revealed the existence of benzylester and -CH(CH3)OH end-groups. Polymerizations conducted at low lactide/catalyst ratios in the absence of an alcohol yield polylactide with a low content of 2-ethylhexanoate end-groups. H-1 and Sn-119 n.m.r. spectroscopy of CHCl3 solutions also demonstrated that SnOct(2) forms strong complexes with both benzyl alcohol and ethyl lactate and weaker complexes with lactide. A similar but weaker complexation was also detected for Bu(2)SnOct(2) in combination with either benzyl alcohol or lactide. A new polymerization mechanism is discussed, assuming the reaction between lactide and OH end-groups bound to a Sn atom via two sp(3)d(2)orbitals.