Burst firing of hippocampal complex spike cells was examined in the awake rat. The results indicated that each complex spike cell tended to show a unique distribution of the number of spikes in each burst. This distribution was stable over time. The mean number of spikes per burst in 21 cells ranged from 1.06 to 4.07. Each subdivision of the hippocampus (CA1, CA3, dentate) contained cells with a wide range of burst distributions.