The purpose of this study was to determine the magnitude of weight gained in collegiate wrestlers between the weigh-in and beginning of tournament competition. Body weight of the qualifiers for the NCAA Division I, II, and III wrestling finals (N = 668) was recorded at the official weigh-in and again approximately 20 h later, before the first round of competition in the tournament. The results showed that on average (+/- SD), wrestlers gained 4.9 +/- 2.4% (3.3 +/- 1.5 kg) of body weight before competing. An inverse relationship was found such that wrestlers in the lightest weight classes gained the most weight (kg) compared with heavier wrestlers (r = -0.45, P < 0.05). Despite the large mean weight gain, the mean discrepancy between first round opponents was 2.1 +/- 3.0 kg and even less when heavyweight wrestlers were excluded from the analyses (1.5 +/- 1.2 kg, N = 607). A significant correlation between weight gain and weight discrepancy of opponents was found (r = 0.65, P < 0.05). collegiate wrestlers, excluding heavyweights, gained significant amounts of weight (3.7 kg average) during the 20-h period prior to tournament competition. The magnitude of weight gain was positively correlated to the degree of weight discrepancy (size advantage) over the opponent; however, because weight gain of some magnitude after the weigh-in was common in most participants, the average discrepancy between opponents was only about 1.5 kg.