The Levey-Jennings chart is a statistical quality control tool used in laboratory medicine to monitor the precision and accuracy of test results over time. It is named after its inventors, Drs. Lawrence Levey and Harold Jennings. The chart displays a series of control measurements plotted against time, with the mean value and the upper and lower control limits represented as lines on the graph. The chart enables laboratory staff to quickly identify trends and shifts in their test results, and take corrective action if necessary. It is an essential tool for ensuring the reliability and accuracy of laboratory testing.