Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by sensation of bloating, abdominal pain, nausea, vomiting, sensation of gas, constipation and diarrhea. SIC is characterized by a lack of clear biological markers which are needed for diagnosis, therefore previous research strives to determine the main factors that contribute to the development and maintenance of the symptoms within the biopsychosocial model. This study examines the relationship of gender, stress and catastrophizing with the intensity and frequency of IBS symptoms. The main aims of this study were the examination of gender differences related to intensity and frequency of symptoms and the bowel movement rhythm, furthermore examination of the relationship between stress and symptoms depending on their temporal relationship, and finally the examination of the effects of catastrophizing on the relationship between stress and symptoms. 86 participantstook part in the study; 71 were female and 15 were male. The age of the subjects ranged from 21 to 80 years. During a two-week period, the subjects' task was to fill in a diary every day before going to bed, which collects data on the daily stress level, the frequency and intensity of IBS symptoms, and the number of stools. After completing the diary, the subjects completed the catastrophizing scale from the Coping Strategies Questionnaire (Rosenstiel and Keefe, 1983). Statistical analysis showed a significant external difference in the intensity and frequency of IBS symptoms, indicating more intense and frequent occurrence in the female sample. A statistically significant main effect of the time lag on the relationship between stress and IBS symptoms was obtained, with the relationship between stress and symptoms being statistically more significant in the zero-lag condition compared to the two different lagged conditions, when one time series precedes the other. A statistically significant effect of catastrophizing on the timed relationship between stress and symptoms was obtained, more precisely, an increase in the connection between stress and symptoms is predicted by an increase in catastrophizing. The results of the study indicate the existence of a higher prevalence of IBS symptoms in the female sample compared to men. Also, stress on the same day significantly affects the intensity of symptoms, with the presence of catastrophizing reinforcing the relationship between stress and IBS symptoms.