The Panic Disorder Severity Scale (PDSS) is a well-established measure of panic symptoms but few data exist on this instrument in non north-American samples. Our main goal was to assess the psychometric properties (internal consistency, test re-test reliability, inter-rater reliability, convergent and divergent validity) and the factor structure of the Spanish version. Ninety-four patients with a main diagnosis of panic disorder were assessed with the Spanish version of PDSS, the Anxiety Sensitivity Index–3 (ASI-3), the Panic and Agoraphobia Scale (PAS), the Beck Anxiety Inventory (BAI), the Beck Depression Inventory-II (BDI-II) the PDSS self-rating form and the Clinical Global Impression-Severity scale (CGI). The Spanish PDSS showed acceptable internal consistency (α = .74), excellent test-retest (total score and items 1–6: α > .58, p < .01) and inter-rater reliability (most intraclass correlation coefficient values for the total score were > .90) and medium to large convergent validity (r = .68, 95% CI [.54, .79], p < .01; r = .80, 95% CI [.70, .87], p < .01; r = .48, 95% CI [.28, .67], p < .01; BAI, PAS and ASI–3 total scores respectively). Data on divergent validity (BDI-II total score: r = .52, 95% CI [.34, .67], p < .01) suggest some need for refinement of the PDSS. The confirmatory factor analysis suggested a two-factor modified model for the scale (nested χ2 = 14.01, df = 12, p < .001). The Spanish PDSS has similar psychometric properties as the previous versions and is a useful instrument to assess panic symptoms in clinical settings in Spanish-speaking populations.