The nutritional status of the canopy foliage in terms of macronutrients (C, N, P, K, Ca, Mg, Fe, Cu, Mn, Zn) has a strong influence on the carbon cycle and energy balance of terrestrial ecosystems and therefore on the energy, water and greenhouse gas fluxes between terrestrial ecosystems and the atmosphere. The leaf mass to area ratio, LMA, is also a widely used leaf functional trait the spatial and temporal variations of which are essential for interpreting canopy exchanges of energy, and CO2. Foliage macronutrient contents and LMA will be assessed at ICOS Ecosystem stations from nutrient analyses and mass/area measurements on periodically collected foliar samples. This document describes how the foliar samples must be selected and taken up and how LMA must be measured at ICOS Ecosystem stations. It also describes how to prepare and ship samples to ETC’s analytical lab, where the nutrient analyses are carried out. The document is structured in different sections with the aim to facilitate the use and application: - Sampling collection and measurements: the general strategy used for the sampling is shortly described. The tools and method used to take the leaves or needles composing the samples together with the collection of metadata requested are presented in order to practically complete the foliage sampling and LMA determination. - Maintenance: in this section the possible maintenance activities are reported. - Submission: it is the section related to the data preparation and submission to the ETC, including the foliar samples. It includes the list of parameters and the way to submit them to the database. It is linked to the BADM system. - Processing: this section describes first how leaf nutrient will be determined by the ETC laboratory and second how the LMA will be calculated. It is important to remind that the exact application of the protocol at station level must be also discussed with ETC in order to reach agreed solutions for specific cases. If a specific part is relevant only for a specific ecosystem or site Class this is also reported in the document.