We have identified seven different beta-thalassemia mutations and one delta beta-thalassemia determinant (the Sicilian type) in 32 members of 17 Hungarian families. The most common mutation is the IVS-I-1 (G-->A) change; its high frequency is comparable to that observed in neighboring Czechoslovakia. Additional mutations are of Mediterranean origin. One rare mutation (initiation codon ATG-->GTG) was identified as an independent mutation because of the absence of known polymorphisms in the beta-globin gene. One new frameshift at codon 51 (-C) was observed in a single individual; hematological data were as expected for a beta zero-thalassemia heterozygosity.