Blue and green cosmetics are sensitive products for microbial contamination and reducing the contamination producing according to Cosmetic Good Manufacturing Practice (ISO 22716), providing proper storage condition and packaging  are effective factors. In addition antimicrobial effective preservatives can be added to protect the cosmetic products.1,2 Generally, preservatives are chemical substrates that are effective on cytoplasm (conjugation mechanism, ribosomes, nucleic acids, thiol groups, amino groups), cell wall and cytoplasm membrane (membrane potential, enzymes, membrane penetration).3 The neutralization of the antimicrobial effect of the preservatives in microbiological quality control of cosmetics is essential for the safety of the tests. The antimicrobial preservative in the cosmetic which is transferred to the medium affects the test negatively. The neutralization process can be carried out according to international standards used in microbiological analysis of cosmetic products. The neutralization of preservatives in cosmetics can be performed by adding of neutralizing agents in solvent, medium and/or washing solution. The agents which are reacted with the preservative groups for the removal of antimicrobial affect are used for this neutralization process which is necessary for the removal of antimicrobial effect. According to European Pharmacopeia 2.6.12. sodium bisulfite for glutaraldehyde and mercury compounds; dilution for sorbates and aldehydes; lecithin, polysorbate 80, saponin for quaternary ammonium compounds, parabens and iodines; thioglycollate for mercurial; thiosulfate for halogens can be used as neutralizing agents.4 Lecithin, polysorbate 80 for parabens, phenoxyethanol, phenylethanol; Lecithin, saponin, polysorbate 80, sodium dodecyl sulphate for quaternary ammonium compounds and cationic surfactants; glycine, histidine for aldehydes formaldehyde-release agents; sodium thiosulphate for oxidizing agents; sodium bisulphate, L-cysteine and thioglycollic acid for metallic salts can be added to the medium, solvent and/or washing solutions according to ISO 21149.5 For the removal of antimicrobial effect, neutralizing agents in proper concentrations should be added to medium, solvents and washing solutions. The addition of these agents with antimicrobial effect should be proved by the studies of conformity. Neutralizing agents react with antimicrobial agents to eliminate the antimicrobial effect.