Iron-deficiency is one of the most prevalent worldwide deficiencies. In the western world, chronic, mostly occult, blood loss is a frequent cause. However, in up to 30% of patients an underlying cause is never found during routine investigations. We describe two male patients aged 20 and 62 years and a 77-year-old woman with mainly fatigue and iron-deficiency showing no abnormalities on endoscopy. In these patients, infection with H. pylori was regarded as the major cause of iron deficiency, and there was lasting normalization of iron status and haemoglobin after successful eradication therapy. Although the underlying mechanism still remains to be established, we recommend investigation for H. pylori infection and appropriate treatment in case of unexplained iron-deficiency. In a number of patients, eradication results in a clinically significant improvement of both iron-balance and status.