Context: Post concussion symptom reports are useful for assessing sport-related concussions. The PostConcussion Symptom Scale (PCSS) allows clinicians an objective measurement of subjective symptoms. Previous studies have used the 22-item PCSS to group the symptoms into related factor structures; these studies have been limited to specific populations. Objective: The purpose of this study was to examine factor structures of high school athletes’ symptoms during the acute stage of sport-related concussions. Design: A retrospective analysis was conducted using data from the State of Hawaii Department of Education’s (DOE) records of Immediate PostConcussion Assessment and Cognitive Test (ImPACT) from School Years 2010-2012. Setting: High school athletes participating in interscholastic athletics were prospectively recruited for the current study. Participants: Participants were participating in 11 sports who sustained a concussion were diagnosed, treated, and followed until return to full participation by the high school athletic trainer. Participants were divided into two groups: group one (N=437, males=292, females=145, mean age 15.49 ± 1.33yrs) who were given the PCSS within 3 days (mean days 1.88± 0.91) of injury and group two (N=231, males=139, females=92, mean age 15.55 ± 1.33yrs) who were given the PCSS within 4-7 days (mean days 5.16± 1.31) of injury. Interventions: All athletic trainers were required to follow a standardized concussion management protocol including post injury assessment utilizing ImPACT. The PCSS within the ImPACT were extracted. Main Outcome Measures: Exploratory Factor Analysis (EFA) was applied to the PCSS of both groups. Factors were extracted using the principal component analysis with orthogonal rotation (Varimax with Kaiser normalization). Results: An EFA provided two 4-factor structure models containing cognitive-migraine, emotional, somatic and sleep clusters. The factors explained 57.08% of variance for group one and 66.01% for group two. Conclusions: The cognitive-migraine cluster between the two groups differed in symptoms loading. Group one symptoms included headache, vomiting, dizziness, fatigue and difficulty remembering. Group two symptoms included trouble falling asleep, sensitivity to light, difficulty remembering and feeling mentally foggy. The changes in cognitive-migraine cluster during the acute phase of a concussion suggest different accommodations should be considered during 0-3 day and 47 days. Identifying how symptom clusters change during the acute phase of a concussion, will allow athletic trainers to make the most beneficial accommodation for athletes during the first week of a sport-related concussion.