The aim of study was to analyse the activity of four biocides. Assessment was made using the methodology described by the Clinical and Laboratory Standards Institute (CLSI); Antifungal Susceptibility Testing of Yeasts, M27-A3 Approved Standard, in: Candida sake, C. albicans, C. lusitaniae and Rhodotorulla rubra. The outcome, related to the culture2 s cut-off value of optical density (O.D.) was analysed statistically (p = 0.05 or lower) proving that Candida albicans was capable of generating strong biofilms, in the resistance setting (p = 0.001).