We report results on the local segmental relaxation (alpha-relaxation) of a cross-linked polyurethane system formed by polycondensation of a triol and a diisocyanate at different connectivity extents. Stable samples with different connectivity extents were obtained either by varying the amount of excess triol (A) or by addition of different amounts of a mono alcohol (B). The glass transition temperature (T-g) increases linearly with increasing connectivity extent for system A, while for system B it is almost constant. T-g is thus mainly related to the amount of urethane groups. The temperature dependence of the alpha-relaxation is independent of the connectivity extent and is the same for both systems. The shape of the alpha-relaxation can be described by a stretched exponential which decreases with an increasing connectivity extent, but in a different way for both systems.