Spontaneous pneumothorax is the most common cause of pneumothorax. We report a case of a 29-year-old healthy woman who presented to the emergency department with a spontaneous pneumothorax caused by a yoga breathing technique called Kapalabhati pranayama, or breath of fire. Yoga breathing exercises are commonly practiced, and a limited number of studies have shown various physiologic benefits of yoga breathing. This is the only known report of spontaneous pneumothorax caused by pranayama, but some other rare causes are noted. This case should illustrate that adverse side effects can occur when one pushes the body to physiologic extremes.