A simple, computer‐controlled high‐speed peak detector for monitoring relative energies in experiments that involve pulsed lasers, is described. In many experiments the laser pulse energy is monitored by feeding the output from a photomultiplier to the 1 M&OHgr; input of an oscilloscope having a bandwidth of about 100 MHz. The computer‐controlled peak detector described in this paper can effectively replace the oscilloscope in such cases. There is, further, an additional advantage that the data can be processed shot by shot. High speed and long hold time are achieved by using two peak detectors in tandem. The first peak detector is capable of tracking fast pulses, but has a low hold time. The second peak detector is slower than the first but has a long hold time. The peak value is held for several minutes without appreciable decay, so that several channels can also be monitored one by one manually with an ordinary volt meter. Its versatility in measuring shot‐to‐shot energy variation of laser pulses, and in real‐time pulse selection are demonstrated. Saturation characteristics of a nitrogen laser pumped dye laser has also been studied with two such peak detectors operated simultaneously. ©1995 American Institute of Physics.