Besides the considerable differences in the intestinal absorption of the different antibiotic classes as described in part I of this paper galenic preparations and the administration in form of a capsule -- tablet or sirup play a major role too. The particle size of antimicrobial drugs in sirup form has to be carefully selected. It should not be too small to prevent a rapid decay of the substance by gastric acid; if it is too large the dissolution of the substance is not fast enough for maximal absorption in the upper intestinal tract. Enteric coating, soluble binders, the dissolution time of a tablet are other important variables in the absorption of orally administered antibiotics. The most important influence on the resorption of orally administered antibiotics comes from the patient. Individual variations in the absorption are exceptionally high with amoxycillin. Different age groups show considerable variations in intestinal absorption which can amount to an extent of a two to threefold increase or decrease over the mean. Simultaneous administration of food or drugs have significant influences on the absorption of certain antibiotics. The pharmacokinetic investigation and bioavailability studies are done on healthy young adults. Diseases of the intestinal tract like acute diarrhea or malabsorption syndromes influence the absorption of orally administered antibiotics to a considerable extent which even renders some drugs completely ineffective. In cystic fibrosis the enteral absorption is retarded and pharmakokinetic parameters sizably altered.