The cytochrome group of the enzymes-electron carriers in the terminal site of the respiratory chain of paraffin-oxidizing yeast C. guilliermondii K-5 has been identified. Spectral peaks of their reduced form correspond to the following wave lengths: c-412, a1-510 and a2-546nm. Variations in the content of cytochrome C of the accumulative culture have been studied. Reduced forms are predominant in the lag-phase and in the phase of exponential growth. This predominance disappears in the phase with negative acceleration and the dying culturt contains a greater number of oxidized forms.