The electronic smcture, local magnetic moments and magnetic susceptibility of Fe, CO and Ni substiNtiond impufities in AI clusten xe calculated withh the framework of the local spindensity approximation and the model of an 'atom embedded in a jellium sphere'.Clusters containing up to 100 atoms are considered. It is obtained that the 3d impurities may be magnetic or non-magnetic depending on the AI cluster size. The impurity magnetic susceptibility is an oscillating function of duster size that results from the size dependence of the position of the virtual bound states relative to the host Fermi energy. The magnetic susceptibility for Fe impurity mm in AI clusters is positive. the magnetic susceptibility for CO atoms oscillates around zero, and the Ni impurity is diamagnetic. The results are in agreement with experimental data far dilute AI-based alloys. Ed -Er. (Ryd) for the following impurities Matrix Fe CO Ni AI cluster, N,, = 6 -0.13 -0.20 -0.28 AI cluster, Nnt = I I -0.04 -0.15 -0.27 AI cluster, Na, = 19 -0.14 -0.23 -0.38 AI cluster, N,, = 23 -0.22 -0.27 -0.35 AI cluster, N , = 30 -0.22 -0.14 -0.30 AI cluster, N,, = 44 -0.07 -0.15 -0.29 AI cluster, Ne, = 56 -0.21 -0.30 -0.44 AI cluster, Net = 66 -0.21 -0.24 -0.34 A1 cluster, N8, = 77 -0.13 -0.19 -0.35 A1 cluster. N , = 89 -0.12 -0.22 -0.34 Bulk AI, impurity-in-jellium model [I71 -0.075 -0.135 -0.246 Bulk AI, spherical solid model [I91 -0.060 -0.088 -0.134 Bulk AI, KKR Green function method [20] -0.059 -0.081 -0.132 Bulk AI. KKR Green function method [211 -0.101 -0.132 Bulk AI, LMm Green function method [