In other words, depending on the date of Pascha, the Apostles Fast can begin as early as May 18 or as late as June 21. Thus, it may be as short as eight days or as long as 42 days in duration. The Apostles Fast may not be observed at all in certain years for those Orthodox using the new calendar as the second Monday after Pentecost may fall on or after June 29, but it is always observed by the Orthodox using the traditional calendar.