Unstable hemoglobins are a group of genetic variants of hemoglobins caused by the mutation of amino acids into alpha and beta globins and, depending on the points and types of mutation, the result can vary from no clinical symptomatology to severe hemolytic anemia. On the present report, we study the case of a female patient who showed a very exuberant hematological picture for the red series, which suggests hemoglobinic changes; this was confirmed following the conduction of the protocol established by Laboratório Médico Santa Luzia for the study of hemoglobinopathies and which was then sent for a reference laboratory: C.D.A. Naoun Laboratórios de Análises Clínicas Hemoglobinopathies Unstable hemoglobin Köln HB Due to the great diversity of mutation points on the globinic structure, as well as the types of mutation by substitution or deletion of amino acids, the unstabilizing forms vary greatly. In this situation, some hemoglobins are discreetly unstable and are not