The production of 𝑍 bosons in association with at least one 𝑏-jet and 𝑍 decaying into muons or electrons is studied. This analysis is done by using proton–proton collisions delivered by the Large Hadron Collider (LHC) at a centre of mass energy of 7 TeV and with data recorded by the CMS detector in 2010, representing an integrated luminosity of 36 pb-1. A final state of two wellidentified muons or electrons and at least one 𝑏-tagged jet are required in order to perform this study. The event yields and shapes of kinematic variables are compared with Monte Carlo predictions from MADGRAPH. The ratio $\sigma (Z + b)/\sigma (Z + j)$ is found to be $0.054 \pm 0.016 (0.046 \pm 0.014)$ in the data for the $Z \rightarrow ee (Z \rightarrow \mu\mu)$ selection, compared to $0.043 \pm 0.005 (0.047 \pm 0.005)$ estimated from NLO theory predictions.