Background Activating receptor ligand for nuclear factor (RANKL) has been identified as a ligand attached to the cell membrane of osteoblasts and odontoclasts. Aim To determine a possible association of sRANKL in saliva and serum with the parameters of metabolic syndrome (MS) in paediatric population aged 8‐12 years. Design This was a clinical, analytical and comparative study. Students between 6 and 12 years with good oral hygiene were included. Anthropometry, clinical analysis, dentobacterial plaque registration were registered as well as sRANKL in total saliva and serum through the ELISA technique. Results A total of 43 children were enrolled, with a mean age of 9.7 (±0.8 years). Contrasting the groups by the presence or absence of the waist circumference above the normal limit, the difference in serum sRANKL concentration was statistically significant ( P ≤ 0.05). A negative statistical significance was found in the correlation between serum sRANKL and HDLc ( r 2 = −0.310, P = 0.046). Saliva sRANKL did not show statistical difference between neither gender nor body mass index and was not correlated with any parameter of the MS. Conclusions A good oral hygiene seems to avoid the effects of MS on the oral cavity.