This document reports the precision and spatial resolution of EOS MLS measurements, estimated fromsimulations of the EOS MLS measurement process. The reader is referred to Waters and Froidevaux (2004)for an overview of the EOS MLS experiment. The simulations use the operational EOS MLS code developed at JPL (Read et al. 2004; Schwartz et al. 2004; Livesey and Van Snyder 2004) including spectroscopic information and instrument parameters from initial calibration (Jarnot et al. 2004). The results are representative of the measurement capabilities of EOSMLS. Clouds are included in the operational code (Wu and Jiang 2004), but have not yet been included in the precision estimates documented here: in the current version a clear atmosphere is assumed. Estimates of the precision of the ice water content (IWC) product for high and low clouds will be included in a future revision. The effects of clouds on the precision of tropospheric H2O, O3 and CO are complicated and depend on the type, amount and altitude of the clouds: it is doubtful that simple simulations such as the present will be enough to characterise these effects. Liquid water clouds will not be included: although these absorb strongly in the frequency region used by EOS MLS, they generally occur below the targeted altitude range. These types of simulations have helped guide some of the EOS MLS instrument design, e.g. feasibility of measuring particular chemical species and placement of spectrometer channels. The current simulations will be useful in planning the scientific exploitation of the EOS MLS data, and serve as a reference to check against the measurement capability in actual operation.