Hereditary alpha tryptasemia (HαT) is found in approximately 7% of the population. Associations with a variety of clinical symptoms including gastric reflux, joint hypermobility, dysautonomia, flushing and pruritus, and hymenoptera allergy have variably been described in prior reports. However, our understanding of this genetic trait is limited by a paucity of published studies, referral bias, and conflicting findings at clinical presentation. The purpose of this study was to assess the clinical phenotype of HαT in a random biorepository population and in patients with and without mastocytosis referred to the allergy clinic. Tryptase copy number allele was assessed using digital droplet PCR. Participants with or without HαT were interviewed and examined by a clinician and surveyed regarding their medical history and symptomology. HαT was identified in 7.5% of the random biorepository samples and in 18% of patients with mastocytosis. There was no difference in the clinical symptomology or medical history of individuals with HαT compared to controls. Average baseline serum tryptase was higher in individuals with HαT compared to controls, but there was no difference in urinary mast cell activation products. Elevated baseline serum tryptase was the only consistent phenotypic marker for HαT in this study. There was a higher frequency of HαT in patients with mastocytosis than in the general population.