SummaryPatients with coeliac disease always excrete more saturated than unsaturated fatty acids with the faeces. If the diet contains practically only unsaturated fatty acids in the form of olive oil, then the fat excretion is normal (C.A. = 95 %). If the diet contains wheat flour instead of rice flour, noticeably more saturated fatty acids are excreted, while the excretion of unsaturated fatty acids remains practically the same. That in this case we have not only to deal with a disturbedfat absorptionis shown by the fact that with a diet of wheat flour + olive oil more saturated fatty acids are excreted than taken up with the diet. From this we can conclude that afat excretionexists in the case of patients with coeliac disease who use wheat flour. This was confirmed by experiments wThereby, on a fat free diet containing wheat flour, considerable quantities of fat were excreted with the faeces. Consequently it must be assumed that a disturbance in the intermediary digestion exists in coeliac disease.Therefore it is very tempting to consider a disturbance in the intermediary fat digestion also in the case of coeliac patients consuming a diet without wheat flour.It was evident that in pancreatic fibrosis also, the steatorrhoea in some measure is caused by fat excretion. In connexion with this, it is important to take into account the possibility of fat excretion, due to a disturbed intermediary fat digestion, being present in other diseases with steatorrhoea: sprue, rachitis, tuberculosis, lambliasis, icterus, etc.