The propositus is a two year old child with a severe hemolytic anemia and increased level of Hb F. The Hbs A, A2 and F were eluted and quantitated by cation exchange high-performance liquid chromatography (HPLC-CE). DNA was isolated from peripheral blood leukocytes by a salting-out extraction procedure. The beta globin gone was amplified and the presence of the beta thalassemia mutation was determined by PCR followed of Reverse Dot Blot. Her hematological parameters were as follows: Hb: 7.0 g/dL, Hct: 24.8%, VCM: 87.4 fl, CHCM: 27.8 fl. The haemoglobin study showed an 97% increase of Hb F and Hb A2 normal. The molecular study suggested the presence of beta(IVSII-829) mutation in trans to deltabeta Thalassemia. The propositus inherited her mother's deltabeta-thalassemia gene mutation and her father's beta(IVSH-829) mutation. This is the first time the diagnosis has been performed in a Venezuelan family at-risk of compound heterozygotes for beta-thalassemia and delta beta-thalassemia.