Research suggests that borderline personality (BP) disorder is associated with reduced pain perception. However, it is unclear whether this is due to qualitative differences observed only in patients, or quantitative differences in dimensional personality traits that can be observed in non-patients. To examine this issue, the BP subscales of the Personality Assessment Inventory (Affective Instability, Identity Problems, Negative Relationships, Self-Harm) were assessed in student participants across two studies of pain and nociception. In Study 1, noxious electric stimuli were delivered to the sural nerve to measure nociceptive flexion reflex (NFR) threshold. Further, subjective pain was assessed via ratings of electrical stimulations at 120% NFR threshold intensity. In Study 2, cold pain was induced by asking participants to submerge their forearm in 33 degrees F water (cold pressor) and keep it there for as long as they could tolerate it while making pain ratings on a mechanical visual analog scale (M-VAS). Pain threshold (latency to M-VAS movement) and pain tolerance (latency to arm removal) were recorded by computer. Study 1 found that affective instability was negatively correlated with pain ratings (r = -.37, p = .05), but not NFR threshold (r = -.02, p = .92). In Study 2, affective instability was positively correlated with pain tolerance (r =.47, p = .02), but not pain threshold (r = .27, p = .21). Other BP traits did not covary with pain outcomes in either study. Together, these data suggest that affective instability is associated with reduced pain perception and may contribute to the hypoalgesia observed in patients with BP disorder. This hypoalgesia does not appear to result from descending inhibition of spinal nociception, because NFR threshold was not associated with affective instability. Additional studies are needed to determine the exact mechanisms involved with BP and pain modulation.