ABSTRACT Background In-training examinations (ITEs) are intended for low-stakes, formative assessment of residents' knowledge, but are increasingly used for high-stake purposes, such as to predict board examination failures. Objective The aim of this review was to investigate the relationship between performance on ITEs and board examination performance across medical specialties. Methods A search of the literature for studies assessing the strength of the relationship between ITE and board examination performance from January 2000 to March 2019 was completed. Results were categorized based on the type of statistical analysis used to determine the relationship between ITE performance and board examination performance. Results Of 1407 articles initially identified, 89 articles underwent full-text review, and 32 articles were included in this review. There was a moderate-strong relationship between ITE and board examination performance, and ITE scores significantly predict board examination scores for the majority of studies. Performing well on an ITE predicts a passing outcome for the board examination, but there is less evidence that performing poorly on an ITE will result in failing the associated specialty board examination. Conclusions There is a moderate to strong correlation between ITE performance and subsequent performance on board examinations. That the predictive value for passing the board examination is stronger than the predictive value for failing calls into question the “common wisdom” that ITE scores can be used to identify “at risk” residents. The graduate medical education community should continue to exercise caution and restraint in using ITE scores for moderate to high-stakes decisions.