To study the willingness of first-degree relatives of axial spondyloarthritis (axSpA) patients to use preventive medication. First-degree relatives of HLA-B27-positive axSpA patients (pre-SpA cohort) (n = 106) completed a survey including scenarios varying in disease risk, side effects, and treatment effect of hypothetical preventive medication and questions about their perceived risk of developing SpA and assessment of the severity of SpA. The willingness to use preventive medication was 63.2–91.5% (with 30–70% SpA risk, respectively) and declined to 27.4–51.9% respectively, when side effects might occur. On a visual analogue scale (VAS) 0–100 mm (totally disagree-totally agree) (median;range), participants were not occupied by the thought of developing SpA (23;13–39), did not assume that they will eventually develop SpA (22;14–35), and consider SpA a severe disease (66;52–78). The willingness to use preventive medication was negatively influenced by their own risk assessment of developing SpA (OR = 1.17, p =.001) and was not primarily influenced by costs and route of administration. First-degree relatives of axSpA patients with a clearly increased disease risk (70%) would largely consider using preventive medication. Their willingness roughly halved by the possible occurrence of side effects. Participants’ perceived risk to develop SpA and their assessment of the severity of SpA negatively influenced the willingness to use preventive medication.