Schizophrenia and rheumatoid arthritis (RA) are both chronic diseases with an estimated genetic component of 60%. While RA is a well-known autoimmune inflammatory joint disease, recent data point to an active immune process also being involved in schizophrenia. Several studies confirmed the negative association between schizophrenia and RA, indicating genetic factors that predispose to the one disorder, while protecting from the other. Macrophage migration inhibitory factor (MIF) and the monocytes surface receptor CD14 are involved in the development and maintenance of chronic inflammation. We therefore investigated if the -G173C single nucleotide polymorphism (SNP) and the tetranucleotide repeat CATT (5 - 8) at position -794 of the MIF gene and the CD14 - C159T transition are candidates for genetic liability to schizophrenia and RA or could explain the negative association between them. In our study 157 schizophrenic patients, 119 patients suffering from RA, and 225 healthy individuals were genotyped. All subjects were Caucasians. The CD14- and MIF-genotypes were equally distributed in all three groups. From our results, we cannot confirm the hypothesis that the investigated genetic mutations within the MIF and/or the CD14 gene are involved in the aetiology of either disease or could explain the negative correlation of schizophrenia and RA.