Montmorillonite (MMT) was modified with dodecylamine, 1,12-diaminododecane, and 1,11-aminoundecanoic acid to prepare CHMMT, NHMMT, and COMMT, respectively. The three clays were mixed with poly(L-lactide) (PLLA) with the aid of chloroform. Depending on the modifiers, PLLA/MMT composites exhibited different mechanical properties and morphology. A completely exfoliated morphology was observed in the PLLA/COMMT composite (PLACO). The PLACO exhibited the best tensile properties among the tested composites because of the finest dispersion of the clay layers. (c) 2006 Wiley Periodicals, Inc.