Gastric cancer is one of the most diffuse neoplastic pathologies in the world whose environmental and molecular causes, although deeply investigated, have not been completely clarified. Besides some well-established etiological factors, such as Helicobacter pylori and E-cadherin mutations, investigations on other possible causes gave contrasting results. Rb family proteins (including pRb/p105, pRb2/p130 and p107) are involved in cell cycle regulation and their function and/or expression is often lost in various kinds of tumours such as lung, bladder, breast and brain cancer. The consequences of RB inactivation in tumours can be very different depending on the context and the type of cancer. Recent evidence indicates that Rb status correlates with a different therapeutic response according to the tumour type and the therapeutic agent. Studies performed on Rb family proteins in gastrointestinal tract tumours suggest that these proteins have an important role in these cancer types. However, owing to contrasting results, further investigation is required to assess whether the expression of Rb family proteins can potentially be used as a prognostic or predictive factor in gastric cancer.