Impulsivity, defined as a tendency to act prematurely or with insufficient forethought, frequently in a risky or inappropriate fashion and often resulting in undesired outcomes, is increased in patients with bipolar disorder (BD) both as a trait, independently from mood states, and as a state, being more pronounced during manic states. Impulsivity is usually assessed as a trait with the Barratt Impulsiveness Scale and as a state with objective tests such as the balloon analog risk task, gambling tasks, go/no-go tasks, single key impulsivity paradigm, and the stop signal task. In latent stages of BD, impulsivity is relatively uncommon but predicts a worsened prognosis, being associated with more comorbidities, functional impairment, substance abuse, more suicide attempts, risky sexual behaviors, as well as more addictive and aggressive behaviors. Impulsive patients with BD can have volumetric and functional changes in the prefrontal cortex, ventral striatum, and the corpus callosum; combined with changes in psychometric tools to assess impulsivity, these abnormalities might guide new screening protocols for this severely impaired subgroup.