Under DD, the compound eyes of the adult cricket,Gryllus bimaculatus, showed the circadian electroretinographic (ERG) rhythm peaking in the subjective night. The rhythm clearly persisted even after optic tract severance. When the optic tract was cut unilaterally, a 24‐hr LD given to the eye of the operated side entrained the ipsilateral eye, but did not entrain the contralateral intact eye kept in DD. Consequently, the ERG rhythms of the two eyes were desynchronized. These results indicate that the ‘optic lobe‐compound eye’ system (OCS) contains the complete circadian system housing photoreceptor, pacemaker and effector for the ERG rhythm.