Introduction: Several studies on late effects of childhood cancer have been conducted during the past decades. To ensure external validation of a study population, the participation rate must be high. This study investigated demographic data in late effect studies and potential factors impacting on participation rates such as cancer type, time since diagnosis and duration of clinical examinations. Procedure: By searching the databases PubMed, Embase and Web of Science and by contacting researchers and clinicians, we identified studies including an invitation to a clinical examination for late effects after childhood cancer. Studies conducted from January 2010 - March 2020 in the Nordic countries were included. Results: We found 80 published studies originating from 16 cohorts. The overall participation rates ranged between 27 and 100%. The majority of studies (eleven studies) were conducted more than ten years after the cancer diagnosis and primarily on hematologic malignancies (seven studies). The highest participation rates were seen in studies of survivors with solid tumors (92%) and the lowest in survivors with hematologic malignancies (67%) and central nervous system tumors (73%). Neither duration of the clinical examination nor time since diagnosis seemed to affect the participation rate. Conclusion: A trend of lower participation rates when recruiting survivors of hematologic malignancies and central nervous system tumors was found. We encourage future studies to describe the recruitment process more thouroughly to improve understanding of the factors influencing participation rates.