The mass-loss process in S stars is studied using 65 S stars from the listing of Wing and Yorka (1977). The role of pulsations in the mass-loss process is examined. It is detected that stars with larger mass-loss rates have a greater amplitude of pulsations. The dust-to-gas ratio for the S stars is estimated as 0.002 and the average mass-loss rate is about 6 x 10 to the -8th solar masses/yr. Some of the properties of the S stars, such as scale height, surface density, and lifetime, are measured. It is determined that scale height is 200 pc; the total duration of the S star phase is greater than or equal to 30,000 yr; and the stars inject 3 x 10 to the -6th solar masses/sq kpc yr into the interstellar medium.