Biodegradable poly(l-lactide) (l-PLA) solution-grown crystals (SGC), which are the lozenge-shaped morphology of unique dimension with one side of 12 mu m, were grown from dilute solution of acetonitrile. Morphological changes by alkaline degradation and mechanical deformation of PLLA SGC were investigated by atomic force microscopy. Although their enzymatic degradation did not show the change of molecular weight, alkaline hydrolysis of the crystals showed strong fragment of small molecular weights. The mechanical deformation of crystals on PET film by elongation showed the microcracks which were almost perpendicular to the elongation direction. These results indicate that alkaline hydrolysis at initial stage occurred in the chain-folding surface and the remained chains were rapidly eroded in small lozenge shape.