In this work, the importance of transient analysis in the design of floating-gate EEPROM's is demonstrated. Anomalous behavior, which was identified during transient measurements, has been simulated using HFIELDS, a general-purpose two-dimensional (2D) numerical device simulator. The corrective action that was taken at the time to eliminate the problem has been analyzed and explained using the simulation results. In addition, the simulator has been used to investigate 2D effects in the device due to process non-idealities.