Biodegradable polyurethanes ureas (PUU) were synthesized by a two step polymerization. First a poly (epsilon-caprolactone) prepolymer was terminated with three different diisocyanates : lysinediisocyanate (LDI), 1,6-hexanediisocyanate (HDI) and 1,4-butanediisocyanate (BDI). Second the prepolymers were chain extended with 1,4-butanediamine. The degradation products of these polymers are non-toxic. The mechanical properties of the PUU are compared with those of three PU’s. Compared to these PU’s, the HDI and BDI based PUU showed a very high resistance to tearing.