Several vacancy-solute complexes in the Al matrix are examined theoretically. In particular, these are V-Cu, V-Cd, V-In, V-Sn, V-Si and V-Fe. We concentrate on coincidence Doppler broadening (high momentum) profiles and positron lifetimes that bring complementary information about these defects. Positron calculations are carried out utilizing the atomic super-position method employing realistic atomic configurations obtained using an ab initio pseudopotential method. In this study we inspect to what extent such defects are detectable and differentiable using positron annihilation techniques. The influence of lattice relaxations around defects on the positron properties turns out to be important and is also debated. The obtained results are discussed in connection with experimental data published in literature. (c) 2005 Elsevier B.V. All rights reserved.