Two clinical studies were conducted to evaluate the tolerance and effects of a copolymer of chitin and beta-glucan, forming the exoskeleton of fungal cell walls, now supplied for cosmetic applications. A 6-week randomized, double-blind, placebo-controlled study was conducted on 13 volunteers with sensitive skin to compare with 0.5-2% formulations chitin-glucan applied twice daily. Biometrological evaluations showed that erythema did not develop, the water retention capacity of the stratum corneum increased and the transepidermal water loss moderately decreased. Another 16-week randomized, double-blind, placebo-controlled study was conducted on 20 men showing signs of ageing skin. A 1.5% chitin-glucan formulation was applied twice daily. Objective biometrological assessments showed a progressive increase in skin firmness and stratum corneum hydration when desquamation and skin roughness decreased. In conclusion, the chitin-glucan formulations appear safe. They significantly mitigate some signs of skin ageing and improve both stratum corneum hydration and skin barrier function.