Agranulocytosis, an uncommon side effect of phenothiazine treatment, usually occurs within the first three months of such treatment and remits after the substitution of another neuroleptic. The authors report one patient in whom the illness took its usual course and two in whom it did not. Of these two, one patient demonstrated agranulocytosis only after years of phenothiazine therapy and the other showed agranulocytic reactions to various neuroleptics.Abstract Teaser