[en] Applying Witten's formula for global gauge and gravitational anomalies to six dimensional supergravities, we find: (a) The perturbatively anomaly free N=4 chiral supergravity coupled to 21 tensor multiplets is global anomaly free for any choice of space-time manifold with vanishing third Betti number (b₃). (b) The perturbatively anomaly free matter coupled N=2 chiral supergravities with arbitrary number of tensor multiplets, whose Yang-Mills gauge groups do not include G₂, SU(2), or SU(3) are free of global anomalies if the theory is formulated on S⁶. In the case of 9 tensor multiplets coupled to supergravity this result holds for any spacetime with vanishing b₃. (c) The N=6 chiral supergravity has perturbative gravitational anomalies, and therefore the global anomalies need not be considered in this case. (author)