This study aimed to ascertain the frequency and type of hematological findings in a defined group of patients with inborn errors on Crete. The key role of these hematological findings in the diagnosis of the inborn errors in daily practice was explored. A variety of hematological findings were obtained from 31 of the 132 subjects who had been referred to the University Hospital of Heraklion. A diagnosis of inborn errors of metabolism (IEM) was confirmed in 21 subjects, but in 12 of them the diagnosis was combined with hematological findings. The hematological findings consist of a neglected area in the diagnosis of the IEM, and cooperation of primary care physicians and neurologists could help hematologists in the management of people with unexplained hematological symptoms and signs.