Ambiguous anomalies and counterterms

We study the ambiguity that exists in the procedure of Zumino et al. in finding a consistent chiral anomaly, and we are led to a simple understanding of the equivalence of Lorentz, Einstein and gauge anomalies. We clarify the mechanism for anomaly cancellation in the ten-dimensional lagrangian of Green and Schwarz. We then proceed to study perturbatively explicit examples in two and four dimensions. (orig.)