Short-term volunteers are susceptible to a wide spectrum of morbidities, mostly infectious diseases preventable with general hygiene and preventive measures. This study aimed to identify the health problems encountered by European short-term volunteers collaborating for 1 month with a nongovernmental organization (NGO) in Cambodia and to describe their characteristics. A prospective, descriptive observational study was conducted on short-term volunteers who collaborated with an NGO in Cambodia during August 2018. Informed consent and sociodemographic, clinical, and preventative health-related questionnaire data were provided by 198 volunteers. The health problems encountered were confirmed in a primary care consultation with healthcare professionals. Univariate and bivariate analyses were performed. The median age of the volunteers was 22 years (interquartile range = 21-24), and 64% were women. Some (18.2%) had allergies, 8.6% had preexisting health conditions, and 10.6% were under regular treatment. A total of 77.3% visited a pretravel consultation clinic, 39.9% completed a specific pretravel health course, 21.7% took malaria prophylaxis, 92.4% received hepatitis A vaccination, and 82.3% received typhoid fever vaccination. Medical assistance was sought by 112 (57.3%) of the volunteers. The average number of health problems was 2.5 (standard deviation = 1.5), and the total number of health problems attended by the medical team was 279. The most common health problems were upper respiratory infections (12.2 per 1,000 person/days), wounds (10.8 per 1,000 person/days), and diarrhea (6.3 per 1,000 person/days). Short-term volunteers experienced a high rate of health problems during their stay in Cambodia, but most of the problems were mild and preventable and resolved quickly. Pretravel consultation and specific pretravel health training seemed to increase disease awareness.