It happens not unfrequently that a provisional diagnosis of general paralysis is made in the insane, which the subsequent course of the case fails to confirm. In the three cases on which this paper is based a diagnosis of general paralysis was made, in one of them quite confidently, and in the two others only as a last resort, because the course of the disease presented so many unusual clinical features. These three cases are specially interesting because a post-mortem examination was made on each of them, and so permitted of a confirmation or otherwise of the diagnosis, and also on account of the very interesting pathological findings.