It is not easy to define haemorrhoidal complaints precisely since this automatically means the entire aetiology and pathogenesis. What Stelzner describes as a complex compound of arteriovenous links in the rectal mucosa with an interlace of unstriated muscles, elastic fibres and connective tissue forms the anatomic base of the "corpus cavernosum recti". This cavernous vascular padding is a crucial component of the continence organ and ensures a gas-tight seal. According to Thomson's studies, haemorrhoids are to be regarded as a consequence of the disintegration of muscular and elastic components, caused by a distal shift of the vascular padding. The changes can cause growth up to prolapse, as well as haemorrhage or congestion. The reasons have not yet been conclusively clarified. Malfunctioning intestines--in particular constipational changes with hard stool--seem to be causal factors. The mechanisms of function and control of arteriovenous links as well as the influence of hereditary, social and cultural disposition continue to be unclear.