Neutrino masses in the R_p violating MSSM

We compute one loop neutrino masses in the R-parity violating Minimal Supersymmetric Model, including the bilinear R_p masses in the mass insertion approximation. To the order we calculate, our results are independent of the Higgs-lepton basis choice. We have a variety of perturbative parameters - gauge, Yukawa and trilinear couplings, and R_p violating masses. Their relative magnitudes determine which diagrams are relevant for neutrino mass calculations. We find new loop diagrams which can be relevant and have frequently been neglected in the past. For the Grossman-Haber neutral loop contribution to the neutrino mass matrix we obtain explicit analytic results.