To assess the risk and severity of IBS in a population of TMD patients. Subjects for the study group were recruited from patients attending the Dental Clinic. Health controls (HC) were recruited among patients? friends and clinic staff. All subjects filled in the RDC/TMD questionnaire and the ROME III questionnaire for the diagnosis of IBS. The IBS Severity Scoring System (IBS-SSS) was used to evaluate the severity of each case of IBS. Categorical variables were compared through the Chi square test. The risk of having abdominal pain was analysed using logistic regression. Twenty-two (46.8%) cases of IBS were diagnosed among TMD patients, whereas only 4 (11.4%) were in the HC group. This difference was statistically significant (?2(1)=11.6; p<.01). The differences in the distribution of IBS-SSS were statistically significant (?2(3)=12.49; p<.05). The regression model resulted statistically significant (?2(5)=24.08; p<.001, R2=.37): abdominal pain was significantly related to nonspecific physical symptoms independent of the other variables. TMD patients had a greater risk of having IBS compared to HC. TMD patients presented also more severe form of IBS than HC.