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The odor of human body has facilitated diagnosis for a long time. Sniffing the body, breath, urine and even feces became one of the useful methods in ancient medicine. For centuries, the sweet smell of the breath was associated with diabetes, the fishy smell was associated with liver disease, measles was associated with the smell of feathers, typhoid with the smell of fresh bread, and tuberculosis with stale beer. Hippocrates also linked the smell of the human body and disease, claiming that the smell of a sick person is different from that of a healthy one. He classified the characteristic odors of the body into sweet, musty, fishy and rotten. The father of chemical analysis of breath was Antonie Lavoisier, who found that carbon dioxide is exhaled by guinea pigs. The pioneer of modem breath analysis was Linus Pauling, who in 1971 presented the results of breath studies using gas chromatography (GC), showing the presence of over 200 substances. Exhaled air containing approximately 78% N2, 17% O2, 3% CO2 and up to 6% water vapor. The exact concentrations of individual inorganic gases depend on many factors, mainly physical exercise, cardiac output, and lung ventilation. A mixture of many volatile organic compounds is a much smaller group of substances at concentrations 100 ppm. The substances in the breath can come from human metabolism and enter into the body by inhaled air and food. Volatile organic compounds present in the breath that can be divided into different chemical classes e.g. saturated hydrocarbons (ethane, pentane, aldehydes), unsaturated hydrocarbons (isoprene), ketones (acetone), sulfur-containing compounds (methyl mercaptan, dimethyl sulfide, dimethyl disulphide, carbon disulphide, carbonyl sulphide) and containing nitrogen (amines). Endogenous substances in the breath can be used to track physiological and pathological processes in the body. Chemical analysis of the breath can provide information regarding biochemical processes in the organism and human health. Compared to many medical diagnostic methods, it is painless, non-invasive and safe. Nowadays, the main purpose of breath analysis is to identify volatile organic compounds that can be used as markers of various diseases. Research focused on detection of lung cancer based on specific volatile organic compounds in the exhaled air is carried out in many laboratories. Rapid and non-invasive methods for early detection of lung cancer and chronic obstructive pulmonary disease is crucial for early diagnosis. This mini review presents background of breath, briefly describes main volatiles, their biochemical origin as well as potential application of exhaled gases analysis.