1. An experiment with a total of 480 hens (Babcock) was carried out from 16 to 38 weeks of age to evaluate the suitability of wet fermented feed (feed water ratio, 1:1.2-1:1.4) for layers, taking aspects of nutrition and gastrointestinal health into consideration. The production performance, egg shell quality, plumage condition, litter dry matter (DM) content, as well as the composition and activity of the intestinal microbial flora were analysed. 2. Fermented feed was characterised by a high concentration of lactic acid (160-250 mmol/kg feed) and a moderate level of acetic acid (20-30 mmol/kg feed), high numbers of lactic acid bacteria (log 9-10 CFU/g feed) and a pH of approximately 4.5. Feed fermentation reduced the concentration of dietary sugar from 32.1 to 7.3 g/kg DM and the phytate bound phosphorus from 2.7 to 1.9 g/kg DM. 3. Fermented feed seemed to loose attractiveness for the birds quite rapidly, resulting in a more aggressive behaviour and a poorer plumage condition than in birds given dry feed. The use of fermented feed reduced the litter DM content. 4. During the experimental period, the body weight gain of hens receiving fermented feed was 80 g higher than of hens fed the dry mash. Presumably because of an extended adaptation time to the feed, the onset of lay occurred later when hens were fed on fermented feed, resulting in non-significantly reduced total egg production (75 vs. 82%). 5. There was no significant difference between groups with respect to the total egg mass production (g/d/hen, 42 and 45 for fermented feed and dry mash, respectively). Throughout the experimental period, the feed DM intake of hens fed with fermented feed was lower than that of hens receiving the dry mash (110 vs. 125 g). From week 26 to 37, fermented feed improved the feed conversion as compared with the dry mash (g feed DM/g egg mass, 2.28 vs. 2.53). 6. The use of fermented feed increased egg weight in the period from 34 to 37 weeks (61.4 vs. 60.0) and increased shell weight (g/100 g egg weight, 10.2 vs. 9.9) and shell stiffness (N/mm, 161 vs. 150) of eggs collected at 37 weeks. 7. The feeding of fermented feed increased intestinal health by acidification of the upper digestive tract, forming a natural barrier towards infection with acid sensitive pathogens, e.g. E. coli, Salmonella and Campylobacter. 8. It was concluded that fermented wet feed offers potential benefits for health and nutrition, but may become suitable for layers only after the practical problems related to this feeding form have been overcome. However, an early adaptation of the birds during the rearing period seems to be necessary.