Poly(L,L-lactide) microspheres were synthesized directly during the ring-opening precipitation polymerizations of L,L-lactide. The polymerizations were carried out in heptane-1,4-dioxane (4:1 v/v) mixed solvent in the presence of various poly(dodecyl acrylate)-g-poly(epsilon-caprolactone) copolymers (poly(DA-CL)) used as surface active agents. Copolymers with different molecular weights, different average number of poly(epsilon-caprolactone) grafts per macromolecule, and different molecular weights of these grafts were used. Poly(L,L-lactide) microspheres with number-average diameters ((D) over bar i(n)) from 2.46 to 4.07 mu m and with polydispersity parameters ((D) over bar(v)/(D) over bar(n), where (D) over bar(v) denotes the volume-average diameter) from 1.08 to 1.45 were obtained. The dependence of (D) over bar(n), and (D) over bar(v)/(D) over bar(n) on the structure and on the concentration of poly (DA-CL) was investigated. The narrow diameter polydispersity ((D) over bar(v)/(D) over bar(n) = 1.08) was obtained when poly(DA-CL), containing an average of 1.3 poly(epsilon-caprolactone) grafts (with (M) over bar(n) = 4700 g/mol) per copolymer macromolecule, was used at a concentration of 1.6 g/L, i.e., below the critical concentration of micellization of this surface active agent (ccm = 5.1 g/L). Poly(L,L-lactide) microspheres contained from 1.5 to 6.6 wt% of the unreacted lactide. The optical purity of monomer (95.4%) and of the corresponding polylactide from microspheres (from 91.0% to 94.9%) indicated that polymerization in the investigated heterogeneous system proceeds with retention of configuration on the chiral carbon atom. The DSC studies revealed that the crystallinity of the poly(L,L-lactide) microspheres was strongly dependent on the thermal history of these materials and on the concentration of the surface active agent used For the polymerization. Microspheres partly composed of crystalline and/or amorphous poly(L,L-lactide) were obtained.