Although several recent reviews dealt with transition metal catalyzed N-arylation of amines (all classes), to date no specific review covering the N-arylation of amidines and guanidines appeared. Amidines and guanidines are considered as fundamental entities in medicinal chemistry. The appearance of these functional groups in drugs, agrochemicals and natural products justifies a separate description of the current status of the literature on the N-arylation of the amidine and guanidine functionalities. Both acyclic and cyclic derivatives are taken into account. For cyclic amidines/guanidines only systems which possess an exocyclic nitrogen atom are considered. This critical review is largely organized by the type of amidine/guanidine and transition metal used and covers literature up to May 2011 (200 references).