The exposition to tobacco smoke is overall: in home, work and public places. For the examination of the presence and concentration of environmental tobacco smoke (ETS) in indoor environments the nicotine and respirable suspended particulates (RSP) are determined. A variety of biomarkers (nicotine, cotinine, thiocyanate, carboxyhemoglobin, protein and DNA adducts) are propose for measurement of exposure to tobacco smoke. The most popular is measurement of cotinine concentration in body fluids (blood, urine, saliva). Plasma cotinine concentration correlated to numbers of cigarettes smoked and to various biological effects of cigarette smoking and exposure to ETS. Other biomarkers as carboxyhemoglobin, thiocyanate, and amines and polycyclic aromatic hydrocarbons adduct can be also use.