Acid sphingomyelinase deficiency (ASMD) is an autosomal recessive disease caused by biallelic pathogenic variants in the sphingomyelin phosphodiesterase-1 (SMPD1) gene. Acid sphingomyelinase deficiency is characterized by a spectrum of disease and is broadly divided into three types (ASMD type A, ASMD type A/B, and ASMD type B). More than 220 disease-associatedSMPD1variants have been reported, and genotype/phenotype correlations are limited. Here we report the first description of all six diagnosed acid sphingomyelinase deficiency cases in Hungary. NineSMPD1variants are present in this cohort, including 3SMPD1variants (G247D, M384R, and F572L), which have only been described in Hungarian patients. All described variants are deemed to be pathogenic. Eight of the variants are missense, and one is a frameshift variant. The treatment of an ASMD type A/B patient in this cohort using hematopoietic stem cell transplantation is also detailed. This study may help to support diagnosis, patient genetic counseling, and management of acid sphingomyelinase deficiency.