Lymphoproliferative disorders are usually characterized by lymphoid infiltrates that demonstrate clonality in contrast to inflammatory or reactive infiltrates of the skin that are polyclonal without detectable monoclonal populations of T-cells. Probably the southern blot analysis of TCR gene rearrangement can help to delineate the reactive from the malignant processes. In this study, we applied the technique on benign reactive processes in the skin. We examined biopsies from positive patch tests from patients with a delayed hypersensitivity reaction. We found the same gene rearrangement configuration in 11 of 17 patients with positive patch tests. The extra band revealed in these cases was situated in the EcoR1 digested DNA lane at the 8.0 Kb, between the 2 germline bands at the 11 Kb and the 4 Kb respectively. This observation was not correlated to the degree of the inflammatory response or to the specific hapten induced reaction. This pattern was not found in any of 107 patients with malignant diagnoses, but also in six of 43 patients with benign diseases. The clinical implication may suggest the presence or development of clonality in benign inflammatory disorders.