A microscopic theory of electron cyclotron frequency (ECE) intensity fluctuations caused by a weak low-frequency plasma turbulence is presented. The emission is treated as acollective process and the ECE signal fluctuations are expressed interms of the correlation tensor of random source-currents of bareelectrons modified by the turbulence. A contribution of the backgroundradiation modulation due to turbulence induced fluctuations of the wavedamping rate is also taken into account. The plasma electron excursionsresulting from drift in the turbulent electric field in the presence ofthe temperature gradient are found to be the principal mechanism of theECE fluctuations. Opportunities for ECE fluctuation measurements usingthe ordinary and extraordinary wave modes radiation at various cyclotronharmonics are analysed.