alpha,omega-Dihydroxypoly(epsilon-caprolactone)s were prepared by polymerization of epsilon-caprolactone (epsilon CL) initiated with Al[(OCH(CH3)(2)](3) (I) and conducted in the presence of HO(CH2)(5)OH (PD) as a transfer agent. Resulting HO-poly(epsilon CL)-OH had ($) over bar M(n) = 400-1500, <($)over barM(W)/($) over bar M(n)= 1.25-1.06, and functionalities f = 1.99-1.93, respectively. GPC traces indicated the complete consumption of the transfer agent. The molecular weights were controlled, at the sufficiently low concentration of the initiator ([I](0) approximate to 10(3) mol L(-1) vs [PD](0) > 10(-1) mol-L(-1)), by the [epsilon CL](0)/[PD](0) ratio. The microstructure of oligodiols was characterized using H-1 and C-13{H-1} NMR spectroscopies. Application of the alpha,omega-dihydroxypolyethers HO(CH(2)CH(2)0)(n)H and HO(CH(2)CH(2)CH(2)CH(2)0)(n)H as transfer agents allowed the A-B-A alpha,omega-dihydroxy block copolymers to be prepared (where A and B are the poly(epsilon CL) and polyether blocks, respectively) having ($) over bar M(n) less than or equal to 3 X 10(3), ($) over bar M(W)/$)over bar>M(n) = 1.08, and f = 1.98. The triblock structure of the copolymers was confirmed by the H-1 and C-13, NMR. Kinetic studies revealed that PD inhibits the polymerization of epsilon CL; however, no inhibition was observed in the presence of the macromolecular diols (($) over bar M(n) > 10(3)).