A biodegradable mixture obtained by melt mixing polyesters comprising (A) an aliphatic polyester obtained from aliphatic diacids selected from the group consisting of azelaic acid, sebacic acid, brassilic acid, mixtures thereof and mixtures of said acids with aliphatic dicarbossilic acids and/or aliphatic hydroxyacids containing more than 50 mole % of azelaic acid, sebacic acid and brassilic acid, and from aliphatic diols; (B) a polymer of lactic acid in which the concentration by weight of A with respect to (A+B) is in the range of 30 to 60% and in which the sum of the fusion entalpy .DELTA.H.sub.A and .DELTA.H.sub.B of the two polyesters in the mixture is greater than the sum of the fusion entalpies .DELTA.H.sub.1 and .DELTA.H.sub.2 of the polyesters prior to melt mixing.