The influence of glucosamine, glalactosamine, glucuronic acid and of some derivatives of these compounds on mucopolysaccharide metabolism and on protein metabolism of primary fibroblast monolayer cultures was studied.  Glucosamine, glucosamine HCl, glucosamine HI and glucosamine sulfate (in concentration of 100 mg/ml each) caused a considerable, statistically highly significant increase of the secretion of mucopolysaccharides by the fibroblasts.  N-Acetylglucosamine and N-acetylgalactosamine were effective too, though to a lesser degree.  Glucuronic acid was without any influence on mucopolysaccharide production.  The protein content of the cultures was not affected by the 7 compounds mentioned so far in concentrations of up to 100 mg/ml.  Galactosamine and betaine glucuronate induced a certain depression of mucopolysaccharide production and simultaneously a decrease of the cellular protein content.