A new case of Hb Providence was discovered in a French Caucasian family presenting a mild polycythemia. Structural and functional studies of the two abnormal fractions (Hb Providence Asn and Asp) have been performed. These confirm the abnormal characteristics of Hb Providence described previously. Red cells containing Hb Providence were fractionated with a Percoll Albumin density gradient. The respective amounts of the two components were determined in the youngest and oldest cells. We observed a slight increase of Hb Providence Asp from 34 to 37% during the life span of the erythrocytes which confirms that the deamidation of Hb Providence Asn to Hb Providence Asp is a fast process, already present and close to its maximum, in the reticulocytes. Both abnormal components are stable in the presence of isopropanol.