The development of the Chilean television industry in the past years runs parallel to two important phenomena: on the one hand, changes introduced in the TV regulatory framework made it possible to introduce cable television, and on the other a Viewing Measuring System was implemented, which provides results in real time. This document intends to summarize the main elements introduced by the measuring system, which forced television channels to make some operational changes mainly related to the new role that instant ratings play in the market. First, we shall briefly describe the architecture of the ON LINE system. The data transmission solution is the outcome of special circumstances that existed in Chile during the implementation stage - 1992- when adequate telephone service coverage was not available. Secondly, we shall describe the main changes introduced by the ratings system into the television industry. This is based on a study involving in-depth interviews with several TV Channel executives linked to the ON LINE service.