1. The possibility of effective optical control of the shape of volt-ampere characteristics of avalanche transistors has been demonstrated. 2. Test samples of avalanche phototransistors have been fabricated and investigated. The parameters of the investigated samples are in good agreement with the calculated values. 3. The high speed of response of avalanche phototransistors for optical triggering of the relaxation circuits has been substantiated experimentally. In particular, such circuits were triggered by short pulses of coherent infrared radiation obtained from lasers. 4. The use of optically controlled avalanche transistors opens up new possibilities in the design of high-speed pulse and logical opticoelectronic devices.