Herpes simplex virus (HSV) infection has been suggested to be one of the etiologic or triggering factors in Behçet's disease. To test this hypothesis, 258 ICR mice were inoculated with HSV type 1 (KOS strain). After the induced infection, 86 mice (33.3%) died, 77 (29. 8%) showed Behçet's disease-like symptoms, and 95 (36.8%) had a healthy, normal appearance or just a single symptom. The symptoms included skin ulcers on the earlobe, neck, abdomen, back or face (57. 1%); eye syndromes (39.0%); partial hair loss (33.8%); genital ulcers (19.5%); bullae (11.7%); arthritis (5.2%); gastrointestinal ulcer (5.2%); and tongue ulcers (3.9%). The induced Behçet's disease-like symptoms are similar to the clinical manifestations of ulcers, uveitis, and arthritis which have been significant in diagnosing Behçet's disease in patients.