Many terms exist to describe radiating leg pain or symptoms associated with back pain (e.g., sciatica or radiculopathy) and it appears that these terms are used inconsistently. We examined the terms used to describe, and the eligibility criteria used to define, radiating leg pain in randomized controlled trials of conservative treatments, and evaluated how the eligibility criteria compared to an international pain taxonomy. Eligible studies were identified from two systematic reviews and an updated search of their search strategy. Studies were included if they recruited adults with radiating leg pain associated with back pain. Two independent reviewers screened the studies and extracted data. Studies were grouped according to the terms used to describe radiating leg pain. Thirty-one of the seventy-seven included studies used multiple terms to describe radiating leg pain; the most commonly used terms were sciatica (60 studies) and disc herniation (19 studies). Most studies that used the term sciatica included pain distribution in the eligibility criteria, but studies were inconsistent in including signs (e.g., neurological deficits) and imaging findings. Similarly, studies that used other terms to describe radiating leg pain used inconsistent eligibility criteria between studies and to the pain taxonomy, except that positive imaging findings were required for almost all studies that used disc herniation to describe radiating leg pain. In view of the varying terms to describe, and eligibility criteria to define, radiating leg pain, consensus needs to be reached for each of communication and comparison between studies.