By means of a stationary radio frequency discharge producing homogeneous plasmas of hydrogen (Ne =1,4 ·1013 cm -3, Te = 1850 °K) and helium (Ne = 2,7·1013 cm-3, Te = 1850°K) , line profiles are measured photoelectrically with high accuracy. With sufficient energy, differences in intensity of more than 3 decades can be recorded. Profiles calculated on the basis of a quasistatic theory taking into account the mutual COULOMB interaction of the particles agree better than 5% with the measured, exclusively pressure broadened, BALMER lines, H8 to H15 . The electron densities determined from the H10 to H14 line differ by not more than 1%. Line profiles of the diffuse series of helium, including the “forbidden” components, have been measured. It turns out that the intensity in the wing of the triplett lines is proportional to Δv-2,5 and in the wing of the first singulett lines is proportional to Δν –2.0. The profiles of the triplett lines have been used to determine the electron density. These densities agree with those obtained from the merging of the last decernable lines.