Hypoglycemia is the most common adverse event associated with insulin treatment in diabetes. The consequences of hypoglycemia can be quite aversive and potentially life threatening. The physical sequelae provide ample reason for patients to fear hypoglycemia and avoid episodes. For these reasons, our purpose in this study was to develop a new measure that explores specific fear of hypoglycemia (FH) in adult patients with type 1 diabetes and to examine its psychometric properties. The instrument developed to assess FH was initially made up of 20 items, of which 18 were negative and 2 were positive, assessed on a 5-point Likert scale (1-5). This scale was completed by 229 patients with type 1 diabetes. Additionally, a structured interview and a closed question called subjective fear of hypoglycemia were included as diagnostic criteria. A factor analysis employing the principal-components method and promax rotation was carried out, resulting in a new scale composed of 15 items. Three factors (fear, avoidance, and interference) were obtained and explained 58.27% of the variance. The scale showed good internal consistency (Cronbach's [alpha] = 0.891) and test-retest reliability (r = 0.908, p less than 0.001), as well as adequate concurrent and predictive validity. The cutoff score that provided the highest overall sensitivity and specificity was set at 28 points. The Fear of Hypoglycemia 15-item scale (FH-15) demonstrated good reliability and validity. This study suggests that the new instrument may serve as a valuable measure of specific FH for use in research and clinical practice. (Contains 6 tables and 1 footnote.)