Using 50 case histories, an attempt is made to clarify the nosographic and clinical validity of fulminating catatonia as an entity amongst the psychoses. Four groups could be established: fulminating catatonia without organic disease; somatic diseases with fulminating catatonia; catatonic excitement states with an intercurrent organic process, and unclassifiable fulminating catatonia. On the basis of this analysis the syndrome cannot be regarded as possessing the characteristics of a special psychosis. Rather it seems more appropriate to regard fulminating catatonia as a nonspecific symptom complex induced by a multilayered causation.