The dynamic surface properties of solutions of pulmonary surfactant (PS) were investigated at various temperatures and in a broad range of surface tensions. The efficient dynamic surface elasticity was determined for the first time in case when the characteristic adsorption time is comparable with the period of surface area oscillations. The mechanical relaxation in the PS adsorption layer is accelerated strongly not only in the course of compression, but also in the course of expansion due to the formation of a sublayer. The harmonic oscillations of the surface area induce stationary oscillations of the surface tension if the characteristic adsorption time does not exceed the oscillation period and the sublayer formation is sufficiently fast. The information on the dynamic properties of the PS adsorption layer allows estimation of the PS efficiency in medical applications.