ABSTRACTIntroduction: The utility of F‐waves in assessing radiculopathies is debated. The aim of this study is to determine the frequency of abnormal minimum tibial F‐wave latencies compared to an F‐estimate and an absolute reference value in patients with electromyography (EMG) confirmed S1 radiculopathies. Methods: A retrospective review of F‐waves in patients with an EMG‐confirmed isolated S1 radiculopathy was performed. The minimum and mean latencies of 8 tibial F‐waves were compared with the calculated F‐estimate and to an absolute reference value, and the frequencies of abnormal responses were determined. Results: Of the 50 patients with an S1 radiculopathy, 4% had prolongation of the minimum reproducible F‐wave latency, and 8% had prolongation of the mean latency relative to the calculated F‐estimate. Conclusions: The minimum and mean F‐wave latencies are infrequently abnormal when compared with an estimated F‐wave latency in S1 radiculopathies and are insensitive in the assessment of S1 nerve root injury. Muscle Nerve 49: 809–813, 2014