A method for utilizing slow-speed EEG (1/4 mm sec) to detect and quantify gross-motor clinical seizures in a chronic monkey model is described. The technique is particularly useful in the detection of small clinical seizures that may occur in studies of drug efficacy. It estimates the reams of paper generated by standard EEG recording (30 mm/sec) that heretofore precluded easy data collation and thereby essentially prevented continuous monitoring of EEG paroxysms. (This method, however, does not allow the detection of single or non-clumped interictal spikes.) The headplug and recording procedures employed in our laboratory are detailed. The technique can be used alone or, for greater precision, in conjunction with either the recording of motor-activity envelopes or a videotape seizure-confirmation system, or both (Lockard and Barensten, 1967; Lockard et al., 1976c). Unlike our motor-activity and closed-circuit TV method for detecting clinical seizures, the technique of slow-speed EEG could be easily employed in other laboratories already equipped with EEG polygraphs. This method also permits the simultaneous recording of slow-speed and standard-speed EEGs (on separate polygraphs) to facilitate periodically the discrimination between artifacts and clinical seizures.