The health effects of exposures to fallout from Soviet nuclear weapons testing among the residents living nearby the Semipalatinsk nuclear test site in Kazakhstan are not well investigated. There are reports with contradicting results coming from the studies conducted on two independent cohorts: “historical” and “new”. Both use different control groups and dosimetric methods. The two cohorts have a high probability of including the same individuals. There is a need to investigate possibilities to merge them in order to avoid duplication of efforts and resources for future studies of the health effects in these populations. The main objectives of our feasibility study include:• developing and testing mechanisms for identification of cohort members in the two cohorts;• identification and testing of data linkage mechanisms;• determination of the outcomes that can be studied (cancer and non-cancer diseases);• setting up and testing procedures for follow-up;• identification of case ascertainment mechanisms and sources, depending on the outcome;• characterization and validation of dose assessment methods used in the two cohorts;• investigation of the feasibility to collect data on confounding factors;• assessing the availability of biological samples and their potential use in the future.The project will bring together scientists from Europe, Kazakhstan and Japan with the aim of developing a proposal for a future prospective full scale epidemiological study to address the dose-effect relationship for both cancer and non-cancer effects from low to moderate chronic doses, if the feasibility is demonstrated. To achieve the overall objective it is proposed to set-up a consortium that have considerable experience in epidemiological studies on populations residing around the Semipalatinsk nuclear test site and/or who have been extensively involved in the low dose risk research. The group will include European and international scientists with expertise in epidemiology, dosimetry, radiation biology and clinical medicine. At the end of the project, a detailed report based on the results of the work conducted will be developed, critically reviewed by the External Advisory Board and recommendations for future research needs will be made, if feasible.Other populations exposed to low to moderate dose radiation like in Fukushima or elsewhere can benefit from the outcomes of studying the unique Semipalatinsk cohort and the results will contribute to a better understanding and quantification of radiation risks for low to moderate chronic doses. The proposed project is in line with the Strategic Research Agenda of MELODI.