[en] A brief pulse of red (R) radiation increased activity and protein content of photosphoenolpyruvate carboxylase (PEPC): this increase was inhibited by cycloheximide. The effect of R was far-red pulse (FR) reversible when R was followed immediately by FR. Thus phytochrome was involved in PEPC regulation in etiolated maize leaves. Both a lag phase and a saturation exists in the process of R induction of PEPC synthesis: the highest PEPC activity was obtained 24 h after R. Etiolated maize leaves of different age showed different sensitivity to R: the highest sensitivity was found in 5 d-old seedlings. 5 min of R was sufficient for inducing PEPC synthesis, and no additional increases were obtained in activity and protein content of PEPC when the R time was prolonged