For the purpose of radiological protection, the International Commission on Radiological Protection (ICRP) has categorised non-cancer effects having a threshold-type dose response as tissue reactions (formerly called deterministic effects), and recommended equivalent dose limits to prevent the occurrence of such tissue reactions. Accumulated evidence has demonstrated that some non-cancer effects arise years or decades following radiation exposure at doses and dose rates much lower than previously considered. In 2011, ICRP recommended a nominal threshold of 0.5 Gy to the ocular lens for cataracts and to the heart and brain for diseases of the circulatory system, independent of dose rate. Research published since continues to advance knowledge. Elevated risks of cataracts below 0.5 Gy have been reported in several cohorts, but limited evidence is available for the risk of cataract removal surgery. For diseases of the circulatory system, increased risks have been reported in various cohorts, in many with a mean dose <0.2 Gy, and in various medically and occupationally exposed groups for doses <0.5 Gy, but the existence or otherwise of a threshold dose is unclear. There is mounting evidence for the radiation risk of normal-tension glaucoma and neurodegenerative diseases of the central nervous system (e.g. Parkinson's disease). In this article, we briefly review recent developments in such late-occurring non-cancer effects and consider the potential implications for radiological protection.