A variety of experimental paradigms have been utilized to study verbal learning and memory ability in patients with epilepsy. One commonly used paradigm, the free recall of a list(s) of related or unrelated words, has revealed a variety of performance anomalies in patients with complex partial seizures (CPS) of temporal lobe origin, but published studies have varied markedly in important methodological details, making it difficult to interpret discrepant findings as well as to assess the generalizability of results. The purpose of this investigation was to simultaneously inquire into several aspects of verbal learning and memory function that have been reported or hypothesized to be compromised in individuals with CPS of left temporal lobe origin. Thirty patients with CPS of lateralized temporal lobe onset [15 left temporal (LT) and 15 right temporal (RT)] were compared with 15 matched controls (NC) on several measures derived from the California Verbal Learning Test (CVLT), i.e., verbal learning ability, immediate free recall, presence of retroactive interference effects, semantic organization, retrieval efficiency, and recognition memory. Compared to RT and NC groups, the LT patients manifested poorer verbal learning ability, impaired immediate memory, and increased difficulty in the retrieval of verbal material from memory store. Compared to NC subjects, the LT group showed poorer semantic organization in their verbal learning and recall. The RT and NC groups were essentially similar in all respects. Finally, the clinical utility of these findings were investigated, and a series of decision rules designed to separate LT from RT patients was derived.