Bad breath is a widespread but still largely taboo problem. The dentist is often the first point of contact for affected patients. Initially, the diagnosis and quantification of halitosis provides objective evidence and helps to find the underlying causes, but it is equally important for monitoring the treatment progress. Most often, halitosis is caused intraorally, thus the dentist will also be responsible for initiating an appropriate treatment. Apart from the simple organoleptic examination without the need for additional instruments, several devices for the measurement of halitosis are available which provide a differentiated analysis of the exhaled air by determining and quantifying the detected volatile sulfur compounds. Keywords: bad breath, halitosis, halitosis measurement, respiratory gas analysis, tongue coating, volatile sulfur compounds