Choice of the most appropriate ear for CI in postlingually hearing-impaired adults is becoming more relevant as more patients are considered eligible for intervention. The aim of this study is to review factors that influence this choice and to formulate a flowchart. An extensive Medline search was performed. Factors can be divided into surgical, audiological, and patient factors. Surgical factors are anatomic variation and otological medical history. Both are divided in absolute and relative contraindications. Duration of deafness and residual hearing are combined in the audiological factor. Likeliness of improvement of speech perception after CI at different durations of deafness is estimated. This is followed by comparison of between-ear differences in duration of deafness. If there is a large difference, above the presented 5% interval, the ear with the shortest duration is preferred. This review and its flowchart are an aid for decision making in the choice of ear for CI. Being as representative of current knowledge as possible, future refinements may occur as new insights are gained.