Abstract: The pattern of distribution of T and B lympliocytes was investigated in a group of patients with Furazolidone drug eruption by means of immunof-juorescence for peripheral blood B cells and Erosette test for T cells, The drug eruption caused by Furazolidone is a specific group of urticarial reactions. A. significant increase in the number of B lymphocytes and CIC, and marked reduction in the number of T lymphocytes in the acute phase were disclosed in patients in comgarison with those of disappearence of the eruptions, There were also marked systemic manifestations and organs involved, It suggests that the drug eruption caused by Furazolidone is a "type Ⅲ serum sickness-like allergic reaction", The changes of nonspecific LTT and CIC were correlated basically with the disease activity,The incidence of drug reaction in administration of Furazolidone for treatment was statistically higher than that for prevention.