ABSTRACT Thirteen mutant genes of the mouse have been scanned for the occurrence of anomalies of glands of the head region and of the Chievitz organ. In eight of these (ic/ic, my/my, Ph/Ph; Xt/Xt, Cd/Cd; fi/fi; or/or and ch/ch) such anomalies have been discovered; most of them are absence or reduction in size of a gland, but increases in size or numbers have also been seen. The anomalies are mainly and possibly entirely local consequences of pre-existing abnormalities of other organs and thus different from the systemic effect of the tabby syndrome. But in at least one instance no local cause for an isolated glandular defect has been discovered.