Because of the dilemma faced by librarians in the selection of suitable microform reading equipment for the 35 mm format, this paper is designed to analyze the problem of reader and micro-image incompatability, to provide a key for readily determining incongruities, to evaluate presently available readers, to provide modification and development suggestions and to consider the possibility of 35 mm microfiche for research materials. Reasons for the ascendency of 16 mm microforms to their present dominant positions are examined and librarians are urged to voice their needs for retaining the 35 mm size essential for research materials. Actions taken by the National Bureau of Standards and the National Library of Medicine supporting 35 mm are cited. (Author)