Background and purpose — In Denmark, all citizens are guaranteed free access to medical care, which should minimize socioeconomic status (SES) inequalities. We examined the association between SES and the utilization of total hip arthroplasty (THA) by age and over time. Patients and methods — Data on education, income, liquid assets, and occupation on 104,055 THA cases and 520,275 population controls were obtained from Danish health registers. We used logistic regression to estimate adjusted odds ratios (aOR) for THA with 95% confidence intervals (CI). Results — Risk (CI) of THA was higher for 45–55-year-olds with lowest vs. highest education (aOR 1.4 [1.3–1.5]), and for those with lowest vs. highest income (aOR 1.1 [1.0–1.2]). The association between education and income and higher risk of THA decreased with increasing age. The risk of THA was lower for persons with lowest vs. highest liquid assets in all age groups and time periods. The risk of THA was higher for persons with lowest education in 1995–2000 (aOR 1.2 [1.1-1.3]), but diminished in 2013–2017 (aOR 1.0 [1.0–1.0]). For those on lowest income there was a higher risk of THA in 1995–2000 (aOR 1.2 [1.1–1.3]), changing to lower risk in 2013–2017 (aOR 0.8 [0.8–0.9]). Interpretation — In a society where all citizens are guaranteed free access to medical care, we observed a social inequality in regard to the risk of THA with a development over time and in relation to age in most of our SES markers, showing a need for more patient involvement by implementing more focused interventions targeted to the most vulnerable patient groups identified as currently living alone, on low income, and with a low level of liquid assets.