We evaluated a bioptic material of appendices from the hospital in Ceské Budĕjovice, obtained from 1977-1981. Of these, 2173 appendices were removed as cases of a clinical appendicitis, 788 for preventive reasons. In the cases of a clinical appendicitis with the incidence of pin worms in the appendix, the histological picture displayed significantly more chronical, inflammatory changes than in acute cases (test chi 2), while in cases of a clinical appendicitis without the presence of pin worms, we found more acute than chronical forms of inflammations. Our results are supported also by an analysis of preventively removed appendices, where again more chronical, inflammatory changes were found in appendices with pin worms.