Orthostatic intolerance is defined as the development of various symptoms during standing that are relieved by recumbency. Postural tachycardia syndrome (POTS) is another nomenclature of orthostatic intolerance. POTS characterized by a heart rate increase ${geq}30$ bpm from supine to standing or >120 bpm at standing without orthostatic hypotension. POTS is a heterogenous in presentation with various pathophysiologic mechanisms. Important mechanisms are hypovolemia, denervation, hyperadrenergic and deconditioning state. There are presented as lightheadness or dizziness, palpitations, presyncope, sense of weakness, tremulousness, shortness of breath. POTS are classified under 3 groups that are neuropathic, hyperadrenergic, and deconditioning POTS. Most patients can be improved from a pathophysiologically based regimen of management.