The internal conversion coefficients were calculated for the transitions in 199Hg using both Hartree-Fock and Hartree-Fock-Slater atomic models. The relative conversion line intensities were measured with the magnetic spectrometers in Prague and Heidelberg. The multipolarities were determined to be: M1+(0.20_+0.03)%E2, pure E2 and M1 +(13.4 _+0.4) % E2 for the 50, 158 and 208 keV transitions, respectively. Allowing for the nuclear structure effect in M1 component we obtained: M1 +(0.15 _+ 0.03) %E2, 2 = 2.4 __ 1.0 for the 50 keV and M1 +(10.9__0.7)%E2, 2=3.8_+0.5 for the 208 keV transitions. Very good agreement was found between theory and experiment for the atomic subshells, K, L 1_ 3, M1 _ 5, N, and 0 + P.