Batch mode processing is compared, using cost-effectiveness, with on-line processing for computer-aided searching of chemical abstracts. Consideration for time, need, coverage, and adaptability are found to be the criteria by which a searcher selects a method, and sometimes both methods are used. There is a tradeoff between batch mode's slower access and lower hardware requirements and on-line's speed but greater expense. Both methodologies involve programs which are constantly changing and, therefore, require information personnel who can be retained easily. (CH)