The neutrophil‐activating protein (HP‐NAP) of Helicobacter pylori is a major 17 kDa antigen of the immune response of infected individuals. Amino acid sequence comparison indicated a high similarity between HP‐NAP and both bacterial DNA‐protecting proteins (Dps) and ferritins. The structure prediction and spectroscopic analysis presented here indicate a close similarity between HP‐NAP and Dps. Electron microscopy revealed that HP‐NAP forms hexagonal rings of 9–10 nm diameter with a hollow central core as seen in Dps proteins, clearly different from the 12 nm icositetrameric (24 subunits) ferritins. However, HP‐NAP is resistant to thermal and chemical denaturation similar to the ferritin family of proteins. In addition, HP‐NAP binds up to 40 atoms of iron per monomer and does not bind DNA. We therefore conclude that HP‐NAP is an unusual, small, ferritin that folds into a four‐helix bundle that oligomerizes into dodecamers with a central hole capable of binding up to 500 iron atoms per oligomer.