The invention relates to the 2-mercapto-4,5-diarylimidazole derivatives of formula (I), wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are defined as in the description. The inventive compounds have an immunomodulatory and cyclooxygenase-inhibiting activity and are therefore suitable for the treatment of diseases that are associated with a disturbed immune system.