Objective Hip cartilage quality is essential for the success of joint-preserving surgery for osteonecrosis. This study aimed to characterize cartilage changes in osteonecrosis of femoral head (ONFH) using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC). Design Fifteen asymptomatic (control) and 60 ONFH subjects were included in this study. The ONFH subjects were stratified in accordance with the Association Research Circulation Osseous (ARCO) classification (n = 15 hips per ARCO stage). All participant hips were investigated using dGEMRIC and theT1Gd data were collected and analyzed. Results T1Gd value was significantly lower in the ONFH group (365.1 +/- 90.5 ms; range 200-498 ms) compared with the control group (546.1 +/- 26.0 ms; range 504-580 ms) (P < 0.001). The T1Gd values of ARCO stage I-IV ONFH were 460.2 +/- 17.3 ms (439-498 ms), 408.9 +/- 43.4 ms (337-472 ms), 359.9 +/- 34.5 ms (303-412 ms), 231.5 +/- 15.1 ms (200-253 ms), respectively. Decreased T1Gd value was found to correlate significantly with increased ONFH severity (P < 0.001). T1Gd value in collapse stage was significantly lower than that of noncollapse stage (295.7 +/- 70.3 ms [range 200-412 ms] vs. 434.6 +/- 41.7 ms [range 337-498 ms]; P < 0.001). Conclusions dGEMRIC identified hip cartilage as abnormal in ONFH, even at early-stage, as represented by decreased T1Gd, and this was further aggravated by ONFH collapse.