A prospective cohort study investigated the association between LDL-C/HDL-C ratio (LHR) and the risk of new carotid plaques in plaque-free adults aged ≥45 years at baseline from low-income rural areas in Tianjin, China. Data were collected in 2014 and followed up to 2019 using carotid ultrasound. During the six-year period, 606 of the 1582 participants (38.3%) developed new carotid plaques. Higher LHR was significantly associated with increased risk, with each unit increase in LHR increasing the risk by 35.9% (OR = 1.359, 95% CI: 1.180–1.566, p < 0.001). The RCS curve showed a non-linear positive association with an optimal cut-off of 1.257 (p for non-linearity = 0.019). LHR > 1.257 was associated with increased risk in both unadjusted (OR: 1.80, p < 0.001) and adjusted models (OR: 1.835, p < 0.001). Subgroup analysis confirmed a consistent association in all groups (all ORs > 1).[1]