The purpose of the present study was to check whether distinct parameters of digestive physiology of large, middle and dwarf breeds of rabbits are different. From special interest was, whether there are pediculiarities in physiology of digestion in Dwarf Rabbits - compared to larger breeds (the nutrition of Dwarf Rabbits has been based on data derived from larger breeds) - to optimize the feeding Dwarf Rabbits kept as pets. Behind this background the feed intake, digestibility of different ingredients and diets, size of the gastrointestinal tract as well as the amount and composition of chyme (6 hours ppr.) of five adult female rabbits of one large (Belgian Giants = BG; bw 7.06 –7.47 kg), middle (New Zealand White = NZ; bw 3.83 – 5.15 kg) and small breed (Dwarf Rabbits = DR; bw 1.58 – 2.32 kg) were proved. In period A the feed intake (rhythm, time, amount) was tested. The feed was offered ad libitum in this period. The rhythm of feed intake was examined when two pelleted diets (complete diet = AFp, grass meal = GGp) and one mixed feed based on entire ingredients (MFn) were fed. To check the time and amount of feed intake, three pelleted diets (AFp, KGp = herbal grass meal, GGp), which were different in crude fiber content (17/18/25 %, dm) and size of the pellets (2.30/9.98/6.45 mm) as well as one mixed feed based on entire ingredients (CF: 10.5 %, dm) were fed. To test the digestibility (period B) the diets were offered restrictively (30 g DM/kg bm) indepent on amounts of diet ingested. Dry matter and chemical composition of the feces (Weende Analysis) as well as the dry matter on proportion to particle size of the hard feces (wet sieve analysis, 7 sieves, diameter of the mesh: 1.4/1.0/0,8/0.56/0.4/0.2/0.1 mm) were measured. Besides pH parameters of the microbial activity as ammonia (ion sensitive electrode), short chain fatty acids (gas chromatography) as well as lipopolysaccharides (LPS; LAL-Test) were recorded. The digestibility was measured under standard conditions with and without (neck collar) ...