The distance (boxing) 19, 1987. While the International Boxing Federation, which had recently broken away from the WBA, continued to hold onto the position there was no documented medical evidence to show a 15-round fight is more dangerous than a 12-round fight, they eventually voted to shorten their championship distance to 12 rounds as well on June 3, 1988. The last heavyweight 15-rounder title fight was on October 16, 1987 between Mike Tyson and Tyrell Biggs. The last middleweight 15-rounder title fight was a World Boxing Board title match on June 7, 1997 in which Jose Alfredo Flores won a split decision over
Heavyweight boxing championship records and statistics of 23, 2019. These lists do not include "The Ring" and lineal championship fights after 1921, although they only include title streaks during which the champion captured "The Ring" or lineal title. Keys: As of 23, 2019. As of 23, 2019. Keys: "As of 24 September 2018". This list includes only major titles, and it does not include lineal championships after 1921. Below is a list of longest reigning heavyweight champions in boxing measured by the individual's longest reign. The list includes both "The Ring" and lineal championships. Career total time as champion (for multiple time champions) does not apply.