The tick Ixodes ricinus (Arthropoda; Chelicerata; Arachnida; Acari) is an obligate hematophagous ectoparasite of vertebrates, and the main vector of tick-borne diseases for humans and animals in Europe. Because the time a tick spends searching for a suitable host can vary from days to years, the length of its life cycle can range from 2 to 6 years. Knowing the age of ticks is thus an important data for understanding the epidemiology of tick-borne diseases, especially for modeling tick population dynamics. Unfortunately, there is currently no appropriate method for determining tick age that has been experimentally validated. Because between each blood meal, the tick uses its lipid reserves while waiting for a new host, in this study we investigated potential triglycerides, a major constituent of tick lipids and a non-renewable energy source, as a marker of aging (i.e., time since last blood meal). Samples analyzed were individual nymphs and adult females of known age coming from our laboratory tick rearing. As individual tick weight are small (around 150 µg dry weight),some technical optimization were conducte for lipids extraction. Total lipids profiles of individual ticks (especially nymphs) were analyzed by HPLC-HRMS (QExactive Orbitrap). By Principal Component Analysis based on potential triglycerides signals, we were able to reveal a gradual change in lipid composition between nymphs aged from 0 to 3 months since the last blood meal, validating the proof of concept of this method for estimating tick age. Potential applications of this method are discussed, as well as its utility for tick-borne disease epidemiology and vector control.