Formaldehyde is classified by the World Health Organization (International Agency for Research on Cancer) as a carcinogen in Group 1. The upper limit allowed for use in cosmetic products as a preservative has to not exceed 0.2%. This study aims to detect and determine formaldehyde level in some cosmetic products available in the local market using acetyl acetone method. Formaldehyde was detected in 77% of the studied cosmetic products (49 samples) despite the fact that most of them were not labeled formaldehyde or formaldehyde donor preservatives (about 70%). The amount of formaldehyde in keratin samples were higher than the allowed limit (0.34% -11.73%) except one sample 0.18%. pH decrease and temperature increase of keratin samples led to an increase of formaldehyde level as a result of its release from preservatives.