An outbreak of norovirus occurred among participants at a 7th grade basketball tournament held February 3-5, 2012 in Kentucky. The Kentucky Department of Public Health (KDPH) contacted 49 teams comprising 573 players. Thirty six teams (73%) reported at least one ill player. A total of 242 persons with acute gastroenteritis were intentified and interviewed, including 154 (27%) of the 573 players, 12 (26%) of the 46 employees, 11 coaches and 65 spectators. Nineteen (8%) of the ill persons sought medical attention including 2 children who were hospitalized. Three persons from 3 separate teams had experienced illness onset before the tournament and one vomited courtside on the first night of the tournament. Symptom onset for 196 (81%) ill persons occurred on days 2 and 3 after the vomiting episode. No common food or water sources were identified as potential vehicles for transmission.Six stool specimens were collected from 5 players and one spectator; all tested positive for norovirus. Five were sent to the CDC for sequencing and results yielded the identical genogroup II type 7 (GII.7) strain, a relatively rare strain of norovirus.