Abstract: The invention relates to a method for detecting non-responders to anti-TNF therapy comprising testing an individual for homozygosity for a single nucleotid polymorphism in the gene coding for the TNF Receptor II. Monoclonal antibodies against TNF-&agr; (infliximab) represent a new treatment for steroid refractory Crohn's disease that result in a remission rate of 30-50% after 4 weeks. Known single nucleotid polymorphisms within the TNF Receptor I and TNF Receptor II were tested for association with the response to the therapy. It was found that individuals homozygote for the mutated allele arginine at amino acid position +196 in the TNF Receptor II or the mutated allele in exon 2 at amino acid position 56 did not respond. Polymorphisms in exon 2 was newly found. None of the individuals homozygote for the mutations in exons 2 or 6 responded. The mutation in exon 2, although a silent mutation, can be used as a marker because it is in a high linkage disequilibrium with the mutation in exon 6.