The preparation Chronicin solutio ad usum vet. (SPOFA) (a 15% solution of CHF-base in propylene glycol) is to be orally administered to poultry in drinking water. The recommended doses (5 ml per 1 of water in chickens and turkey-poults and 3 ml per 1 of water in ducklings) produce, in the blood serum, CHF concentrations which act bacteriostatically on sensitive microbial strains [chickens--mean 2.60 micrograms per ml (0.71--6.25), ducks--mean 2.11 micrograms per ml (0.87--4.72)]. After dilution, the preparation is stable in the drinkers at least 24 hours and does not reduce the intake of drinking water in short-term administration. CHF residues remained in the organs of hens six days after the five-day therapy and in the eggs of hens nine days after the therapy. It is recommended, therefore, to respect a nine-day protective period in tissues and a 12-day protective period in eggs (between the end of therapy and processing for consumption).