Antigens and immunoglobulins are important biological entities. Interaction of these components is being considered as a major criterion to assess the health status in veterinary and medical science. Antigen-antibody reactions are highly specific. This interaction between antigen and antibody has been used as the principle of immunoelectrophoresis. This technique has got tremendous applications in basic and applied health science. The present chapter describes principle, process, types, applications, advantages, and limitations of various types of immunoelectrophoresis. This information will be very useful for the students of immunology and scholars who need to develop an understanding of immunoelectrophoresis and its applications.