Bad breath is an oral health condition characterized by unpleasant odor from the oral cavity. The origin of halitosis is associated with different oral pathologies, but it may be related to systemic conditions in 15% of the cases. We examined 55 patients with various hepatic and gastrointestinal diseases. With an apparatus to measure bad breath we investigated the levels of odor in patients. The apparatus quantifies volatile sulfur compounds, hydrogen sulfide, mercaptan, dimethyl sulfide and hydrocarbon from the mouth on a scale from 0 to 5. We compared the obtained results with those of 79 patients with general good health. Our studies indicate that the levels of bad breath in the first group were significantly higher in men (0.99) compared to those of women (0.41), more than two times, which is in contrast to the group of patients without systemic diseases. We registered the following average values for bad breath -0.65 in younger patients (20-50 years) and a higher one -0.89 in older patients (51-78 years). Older patients showed higher values of bad breath. Men have halitosis more often (67%) than women (32%).As bad breath is caused by factors outside the mouth in only 15% of the cases, most likely, general illness cannot change this parameter.