The working, health and zoohygiene problems of keeping chickens (45,000) in TEROZ type windowless houses on deep litter with controlled light regimen and hens (75,000) in cages were the subject of study for 3 years. The poultry was fed on factory-produced feedstuffs with the then permitted addition of CTC in amounts of 20 g/l tonne. Except for the low intensity of illumination in the chicken house (10-1.1 1x) and with the observation of the prescribed technology, the working environment is favourable. The state of health of the employees did not differ essentially from that of other groups of workers in aggriculture. The use of CTC resulted in a growing number of resistant microbial strains (Staphylococcus aureus, Proteus mirabilis, E. coli, etc) which led to the banning of its use and replacement by other biostimulants. Every type of large-scale poultry farm should be designed as a whole including the chicken incubator, the egg sorting station, the slaughter house, the use of waste matter and sewage disposal and should be previously tried out experimentally by a group of experts concerned with the given problems, before being introduced into wider use.