Human heavy chain ferritin (H-ferritin) was cloned from human heart cDNA library and expressed in Pichia pastoris. The H-ferritin transformant was cultivated by fed-batch and the cell mass reached about 52 g cell dry wt l(-1) after 150 h. In atomic absorption spectrometry analysis, intracellular content of iron in H-ferritin transformant was measured to 3038 +/- 72 mug g(-1) which was 9.6-fold more than that of control strain.