The relative photodissociation frequency and direct transmittance of O2 can be derived from parametric formulae for 500 cm-1 intervals in the 175-202 nm spectral region that corresponds to the domain of the bands of the Schumann-Runge system. The parameterization is obtained by comparison of detailed calculations (0.1 cm-1 intervals from 115 to 15 km) from Nicolet et al. (1987, Aeron. Acta A, No. 318, 340 pp.; 1989, Planet. Space Sci. 37, 427) with formulae that depend on the solar zenith angle and the O2 column abundances. The overall similarity between the results of the detailed calculations and of the parameterization that incorporates the requisite constants implies that this new set of practical transmission functions and relative photodissociation rates for O2 is appropriate for atmospheric modeling in the mesosphere and stratosphere.