This paper reviews high voltage integrated circuits, their isolation methods, and device features. Conventional Junction Isolation can be used for voltage requirements >200 volts if special upward-downward diffusions are employed or if the RESURF principle is applied. Self Isolation is limited to common source arrays. Dielectric Isolation is most versatile and area efficient. MOS-Bipolar combination devices, complementary designs, and on-chip logic are the trends in HVIC's.