Stomach cancer and bowel cancer are equity issues that contribute to morbidity and mortality for Māori. Both cancers can be prevented using a simple and inexpensive stool test. A bacterium, H. pylori, is the main cause of stomach cancer. Māori have higher rates of stomach cancer, and much higher rates of H. pylori infection, than Europeans. H. pylori can be detected using a simple stool test. Stomach cancer can be prevented by treating H. pylori with antibiotics. The chance of dying of bowel cancer can be reduced by at least 16–22 percent using a screening stool test. However, participation of Māori in a national screening programme that uses the stool test is lower than for all ethnicities. The aim of this randomised-controlled full study is to determine whether adding H. pylori screening to standard bowel screening affects screening participation. We will apply a co-designed, Kaupapa Māori-based combined screening methodology.