We investigate regularity properties of molecular one-electron densities ρ near the nuclei. In particular we derive a representationwith an explicit function F, only depending on the nuclear charges and the positions of the nuclei, such that μ ∈ C 1,1 (R 3 ), i.e., μ has locally essentially bounded second derivatives. An example constructed using Hydrogenic eigenfunctions shows that this regularity result is sharp. For atomic eigenfunctions which are either even or odd with respect to inversion in the origin, we prove that μ is even C 2,α (R 3 ) for all α ∈ (0, 1). Placing one nucleus at the origin we study ρ in polar coordinates x = rω and investigate ∂ ∂r ρ(r, ω) and ∂ 2 ∂r 2 ρ(r, ω) for fixed ω as r tends to zero. We prove non-isotropic cusp conditions of first and second order, which generalize Kato's classical result.