Monolayers of polyamidoamine (PAMAM) dendrimers (generations 3.5 through 10) are prepared via electrostatic self-assembling from water solutions. Their thickness, morphology and mechanical stability are studied by scanning probe microscopy (SPM). A conformational state of dendritic macromolecules is discussed and compared to polymer scaling in the solution and recent molecular dynamics simulation results. The proposed model of molecular ordering assumes highly deformed (compressed along the surface normal) ellipsoidal shape for macromolecules in condensed monolayers. The molecular dimensions (thickness) versus molecular mass dependence is described by a scaling law with the exponent alpha = 0.28 being in-between values typical for dendrimer solutions and for a globular state.