In this paper, we present a temperature-controlled system for MEMS electrical resistance heaters without a temperature sensor. To rapidly control the heater temperature, the microheater system developed consists of a power supply, power amplifier, digital ${underline{P}}roportional-{underline{I}}ntegral-{underline{D}}ifferential$ (PID) controller, and a quarter bridge circuit with the microheater and three resistors are nominally balanced. The microheaters are calibrated inside a convection oven to obtain the temperature coefficient with a linear or quadratic fit. A voltage amplifier applies the supply voltage proportional to the control signal from the PID controller. Small changes in heater resistance generate a finite voltage across the quarter bridge circuit, which is fed back to the PID controller to compare with the set-point and to generate the control signal. Two MEMS microheaters are used for evaluating the developed control system - a NiCr serpentine microheater for a preconcentrator and a Nickel microheater for ${underline{P}}olymerase;{underline{C}}hain;{underline{R}}eaction$ (PCR) chip.