The MCC has given its backing to the continuation of five-day Test matches, amid debate over whether cricket's longest format could be shortened.
The International Cricket Council (ICC) has raised the possibility that Tests after 2023 could be cut to four days.
The MCC's cricket committee and world cricket committee have discussed the issue.
A statement said: "Both committees believe that Test cricket should continue to be played over five days."
However, the statement did acknowledge the "benefits that four-day Test cricket could bring".
MCC remains the guardian of the laws and spirit of cricket, while its world cricket committee is an influential independent panel of former and current players and umpires, which meets twice a year to discuss cricketing issues.
Test cricket has been standardised at five days since 1979, though in 2017 the ICC did permit for certain matches to be played over four days, such as England's Test against Ireland at Lord's last summer.
Since the prospect of all matches becoming four days was raised, a number of international players, including England Test captain Joe Root, have spoken out in support of the five-day game - although the England and Wales Cricket Board said it "cautiously" supported a switch to four days as a possible way of easing the strain on players and the international schedule.