A solid‐state electronic integrator capable of integrating and digitizing small currents has been developed. In a recent experiment, pulsed proton beams with an average value of 10−9A have been integrated and measured with a 0.1% accuracy. Pulsed or direct currents can be measured accurately down to a lower limit imposed by uncompensated variations of the order of 10−13A in input leakage current. The current to be integrated is applied to a Miller integrator circuit which employs a commercially available solid‐state operational amplifier. A diode‐switched charging circuit gated on and off by the integrator output voltage ``pumps down'' the integrator capacitor with discrete units of negative charge, simultaneously delivering digital output pulses to an external counter. An output voltmeter provides analog readout of residual fractional charge increments.