Neutropenia encompasses a family of neutropenic disorders, both permanent and intermittent, ranging from severe (<500 neutrophils/mm(3)) to mild (500-1500 neutrophils/mm(3)), which may also affect other organ systems such as the pancreas, central nervous system, heart, muscle and skin. Neutropenia can lead to life-threatening pyogenic infections whose severity is roughly inversely proportional to the circulating neutrophil counts.When neutropenia is detected, an attempt should be made to establish the etiology, and to distinguish acquired forms (the most frequent, including post viral neutropenia and autoimmune neutropenia) and congenital forms (rare disorders) that may be either isolated or part of a complex rare genetic disease. We report on a male patient initially diagnosed with isolated neutropenia who later turned out to be affected with Barth syndrome, a rare complex inherited disorder.