Background: Halitosis is the presence of unpleasant or foul smelling breath. The origin of halitosis may be related to both systemic and oral conditions, but a large percentage of cases, about 90%, is generally related to an oral cause. The aim of this study was to compare the concentration of urea and uric acid in patients with halitosis and people without halitosis. Materials and Methods: In this case-control study, concentration of urea and uric acid was compared between two groups: (1) persons suffering halitosis (2) control group without halitosis. Each group includes fifty patients. Unstimulated saliva was collected in both groups. Then, concentration of urea, uric acid, and creatinine was determined. The results were statistically analyzed with SPSS software version 14 (SPSS Inc., Chicago, Illinois, USA) by t-test (α = 0.05). Results: Results showed that salivary urea and uric acid concentration in halitosis group were significantly greater than control group (P < 0.05). Salivary creatinine concentration in halitosis group was significantly lower compared to control group (P < 0.05). Salivary urea and uric acid concentration to creatinine ratios were higher in halitosis group than control group, and significant differences between them were existed (P < 0.05). Conclusion: According to the results, urea and uric acid concentration show increase in patient suffering halitosis, and this increase may result in oral malodor.