A laboratory investigation was conducted in order to evaluate the properties, the groutability and the effectiveness of microfine cements. Four gradations from CEM II/B-M (according to EN 197-1) type of cement were used having nominal maximum grain sizes of 100 μm, 40 μm, 20 μm and 10 μm. The properties of suspensions, with water to cement ratios of 1:1, 2:1 and 3:1 by weight, were determined in terms of viscosity, bleeding, setting times and unconfined compression strength. Groutability and effectiveness were evaluated by conducting one-dimensional injections into five different, clean sands using three specially constructed devices. The effectiveness of cement suspensions was quantified by conducting unconfined compression, triaxial compression and permeability tests on grouted sand specimens. Groutability of cement suspensions increases with increasing cement fineness and water to cement ratio. Microfine cement suspensions with water to cement ratios of 2:1 and 3:1 can penetrate into medium to fine sands. Groutability predictions by conventional criteria are not always confirmed by laboratory injections. Sands grouted with microfine cements obtained unconfined compression strength values of up to 3 MPa and, in terms of the Mohr-Coulomb failure criterion, exhibited significant cohesion (up to 1360 kPa). The permeability coefficient of the sands was reduced by up to 5 orders of magnitude.