This research aims to study hydroquinone contamination in skin whitening cosmetic skin purchased. Online sample of 212 cosmetic skin products was taken during in January 2012. Tested cosmetic products for whitening body skin, findings for underarm whitening and cosmetic products to reduce skin tone of the nipples use Hydroquinone Test-kit from Medical Sciences Ministry of Public Health Thailand and findings positive tested results of 25 samples. This study can conclude that there are some safety concerns regarding skin cosmetic purchase from the internet. As the result, the Ministry of Health could conduct inspections to control the cosmetic skin products and/or inform consumer of the danger, which are sale online in order to protect the increase of inspection or impose more penalties to monitor and prevent the sale of cosmetics that might cause harm to the consumer.