In the present paper we correlate clinical data, as well as histopathological, immunohistochemical and molecular biology methods, with the occurrence of both forms of inflammatory bowel disease (IBD) i.e. ulcerative colitis and Crohn's disease. We found that patients with a history of Epstein-Barr virus (EBV) or cytomegalovirus (CMV) infections, as well as steroid treatment, had increased susceptibility to the development of IBD. The diagnosis of IBD was confirmed by histopathology. Previous infections by EBV and CMV, as well as M. tuberculosis, were proved by PCR-based techniques and in situ hybridization. We found PCR-proved latent viral infections in 30-50% of the IBD patients we studied. However, we were unable to prove the presence of viral antigens by immunohistochemistry for EBV or CMV. We found positive correlations between the presence of anti-CMV IgG, as well as PCR-positive results for M. tuberculosis with an ulcerative colitis diagnosis. Additionally, up to 80% of IBD patients used steroids, which was found to be correlated with a diagnosis of Crohn's disease. Our data may support the theory that IBD could be related to previous viral infections and the use of steroids.