A screening procedure for porphobilinogenuria was instituted because there are 4 reasons to expect a higher rate of hepatic porphyria among psychiatric patients than is generally found in other patients. First, acute intermittent porphyria is so closely associated with psychiatric disorder that Roth1 claimed "porphyria occurs with special frequency, if not exclusively, amongst people with severe neurotic personality disorders. It is probable that the psychoneurosis plays an important part in the pathogenesis of the disease and in determining the time of onset of the acute attack." Case reports2 show the connection between "mental stress" and precipitation of an attack of acute intermittent porphyria. If such a correlation between psychiatric disorders and acute intermittent porphyria really exists, then one can expect that an even larger proportion of the cases of acute intermittent porphyria will be found in the population of a psychiatric