This study describes the results regarding the evaluation of retention efficiency by humans of hydroxybenzenes (phenols) from mainstream cigarette smoke. Over twenty phenols were evaluated in the exhaled smoke of a commercial cigarette with 10.6 mg 'tar' [U.S. Federal Trade Commission (FTC) `tar' is defined as the weight of total particulate matter minus nicotine and water]. The test was performed on ten human subjects. The exhaled smoke was collected using a vacuum assisted technique that avoids strain in exhaling the smoke. The study showed that the phenols were retained with high efficiency from cigarette smoke, typically above 80%. Only 4-ethylresorcinol, and C3-dihydroxybenzenes (C3 indicating any alkyl with three carbon atoms) were retained less efficiency with retention values around 70%. The high retention of this class of compounds was expected since phenols are polar compounds with relatively low molecular weights between 94 (for phenol) and 152 (for a propyl-dihydroxybenzene).