Patients with panic disorder and psychiatrically healthy control subjects performed a dual priming task whereby they viewed either lexical or non-lexical prime pairs before naming a target that had either threatening (e.g. collapse) or positive (e.g. cheerful) meaning. Lexical prime pairs comprised a threat word and a positive word, and non-lexical prime pairs comprised two rows of asterisks. Suggestive of a bias for encoding threat cues, panic disorder patients (under some conditions) were faster to name lexically primed threat targets than lexically primed positive targets. These data are consistent with the hypothesis that panic disorder is linked to an encoding bias for threatening relative positive information. A cognitive bias for selectively encoding threat cues may figure in the maintenance of anxiety states, such as panic disorder.