Because highly pain-sensitive normal individuals may be predisposed to more pain over time we argue that some may eventually develop chronic pain syndromes, like fibromyalgia (FM). Central-sensitization which can be assessed by temporal-summation-of-second-pain (windup or WU) and by its maintenance (WU-M), can predict clinical pain. We hypothesized that similar to FM-patients, pain-free sensitive normal subjects (sNC) would show evidence of hyperalgesia compared to normal controls with average pain sensitivity (aNC). Methods: We enrolled 20 female sNC, 112 aNC, and 134 FM-patients. Pain-sensitivity of all subjects was determined by WU adjusted to each subject's heat-sensitivity. sNC qualified if their WU-temperature was < 49.5C, well within the range of most FM-patients. Central-sensitization was tested by WU-M at 0.17 and 0.08Hz, tender-point count by dolorimetry. Negative-affect was measured by VAS (0-10). Results: Similar WU was achieved in all subjects. Mean WU-temperature was 48.6 and 48.0 degC for sNC and FM-patients, respectively (p > .05). WU-temperature for aNC was 51.3 degC. Tender-point count was significantly lower in sNC and aNC than FM-patients (6.7 and 4.3 vs. 16.5; p < .05). Similarly, mean ratings of depression, anxiety, frustration, anger, and fear were significantly lower in sNC and aNC than FM-patients (p < .05). WU-M at 0.17 and 0.08Hz was highest for FM-patients and lowest for aNC. WU-M of sNC was intermediate at both frequencies (p < .05). Conclusions: Despite similar heat-pain sensitivity, pain-free sNC had fewer TP, lower ratings of negative affect, lower WU-M than FM-patients. However, compared to aNC WU-M was higher in sNC, indicating increased central-sensitization in this group, but lower than found in FM. Therefore, increased heat sensitivity in sNC is associated with central-sensitization and thus increased risk for future pain, including FM.