Background/Aims: This pilot study aims to analyse the potential benefits of an aquatic exercise programme on the health-related physical fitness and quality of life of people with Down syndrome, as well as to identify the impact that such a programme might have on the self-perceived quality of life of their parents/caregivers. Methods: A total of 14 adults (mean age 37±7.24 years) carried out an aquatic exercise programme for 3 months. Health-related physical fitness and self-perceived quality of life were assessed by means of the Assessing the Levels of Physical Activity and Fitness battery and the World Health Organization Quality of life Questionnaire, respectively. Findings: No significant impact of the programme was observed on any of the variables tested. Conclusions: There was no evidence to support that water-based exercise might be a useful exercise intervention to improve health-related physical fitness and quality of life in adults with Down syndrome. The self-perceived quality of life of the parents/caregivers did not seem to be affected by this kind of intervention either. Future randomised controlled studies with larger samples are needed to confirm these findings.