In a family of Spanish origin, five individuals presented a heterozygous alpha(0)-thalassemia (alpha-thal)-like phenotype. All had a -alpha(3.7) deletion with the recombinant alpha gene carrying the Hb Suan-Dok [alpha109(G16)LeuArg] mutation, proposed to be thalassemic. Thus, the abnormal chromosome carried an alpha(0)-thal-like allele that has to be taken into account for genetic counseling and prenatal diagnosis. The possibility of Hb H disease or hydrops fetalis should be considered when this allele is associated with alpha(+)-thal or with another alpha(0)-thal, respectively. Other described genotypes associated with Hb Suan-Dok are discussed.