Antisera were produced in rabbits by inoculation of precipitates cut out of second dimensional agarose gels from crossed immunoelectrophoreses. The precipitating antigen chosen (antigen no. 1) had previously been identified as specific for herpes simplex virus type 2. Crossed immunoelectrophoretic analysis of the produced antisera revealed that the antisera contained a high concentration of precipitating antibodies that reacted exclusively with antigen no. 1 and a minor antigen with the same electrophoretic mobility. The produced antisera were useful in the typing of herpes simplex virus isolates by rocket immunoelectrophoresis.