Background This study evaluated the relationship between neuroticism (N), a probable risk factor for emotional disorders, and modulation of startle reflexes (SRs). Methods One hundred thirty-two adolescents with varying levels of N but without anxiety or depressive disorders were evaluated in contextual cue and explicit threat cue paradigms. Results Within the explicit threat cue paradigm, N potentiated SRs more in conditions that were intermediately associated with threat of an aversive biceps contraction than conditions that were the furthest from and conditions that were the closest to the same threat. Also, N potentiated SRs across the entire experiment, regardless of experimental conditions, in male and not in female subjects. Conclusions These results suggest that adolescents with high levels of N show greater sensitivity to contexts intermediately associated with threat. Results are discussed in comparison with other studies of groups at risk for anxiety and depressive disorders.