Abstract Background Little is known about the clinical presentation and course of novel H1N1 influenza in summer camps. Objectives To describe the clinical course and evaluate the effect of influenza treatment in a summer camp population. Study design Two large influenza outbreaks occurred in university-based residential camps between May 21 and August 2, 2009. Through active daily surveillance, medical evaluation at symptom onset, and data collection during isolation, we describe the clinical course of a large outbreak of novel H1N1 influenza. Results Influenza-like illness (ILI) was documented in 119 individuals. Influenza A was confirmed in 66 (79%) of 84 samples tested. Three early samples were identified as novel H1N1. ILI cases had an average age of 15.7 years and 52% were male. Sixty-three were treated with oseltamivir or zanamivir, which was initiated within 24 h of diagnosis. Cough, myalgia and sore throat occurred in 69, 64 and 63% of cases, respectively. The highest temperature over the course of illness ( T max) occurred within 48 h after symptom onset in 87.5% of individuals. Average T max was 38.4 °C (range 36.1–40.2 °C). Among confirmed influenza cases, 69% defervesced by 72 h and 95% defervesced by 96 h. Defervescence at 72 h was not different in the treated and untreated groups ( p = 0.12). Conclusions Novel H1N1 generally has a mild, self-limited course in healthy adolescent campers. Defervescence occurred within 72 h and was unaffected by treatment.