The goal of software inspection is to identify defects and to measure the product and inspection process quality. Software development products that are suspected to contain a substantial number of defects after inspection may be subject to a second inspection cycle (reinspection). So far, very few empirical results can be found on reinspections.This paper reports on a controlled experiment that compares the effect of two inspection cycles. 31 teams reinspected a software requirements document, after defects found during the initial inspection had been removed. We present data on effectiveness, efficiency, net gain, and return on investment from second inspection cycle, and compare these results with data from the initial inspection.Models in literature suggest decision criteria when to reinspect, based on assumptions on relationships of variables between the two inspection cycles. With experiment data, we evaluate these assumptions and the correctness of their decision criteria.Results of the experiment strongly support considering reinspection as an option to improve product quality.