We report on two siblings with beta(+)-thalassemia intermedia. Molecular studies of the beta-globin gene indicated that the patients are homozygous for the -87 (C-->T) mutation. This genotype has not been previously described. Homozygosity for the -87 (C-->T) mutation produces a mild form of beta(+)-thalassemia associated with moderate Hb F elevation (26-38%) and highly elevated Hb A(2) (10-8.6%) levels, respectively. Hematological parameters of homozygous -87 (C-->G) and -87 (C-->A) mutations, and compound heterozygous patients with either C-->T, C-->G, or C-->A at -87 and one of the severe beta(+)- or beta(0)-thalassemia mutations, are given for comparison.