Over the decade from 1979 to 1989, significant advances have been made towards the study of transport characteristics of commercial polymer films. From a perusal of the literature in this area it is found that more than 400 patents have been published. Of these, about 300 appeared in the Japanese language and the remaining are available in other languages including English. It is, therefore, beyond the scope of any authoritative review to include the full details of all the patents. In this review we attempt to include only the representative data available from the chemical abstracts.