Artificial insemination has been increasingly used for the production and preservation of semen from elite bulls. However the prediction of fertility of these animals is obtained by evaluation of different semen parameters. In semen analysis, the sperm structure integrity is of major importance (Neild et al., 1999). Tests that evaluate the integrity of sperm plasma membrane include the analysis of biochemical function and membrane permeability to dyes (Brito et al., 2003). The hypoosmotic swelling test (HOST) evaluates the biochemical activity of intact plasma membrane due to water influx into the cells (Correa & Zavos, 1994; Rota et al., 2000). Propidium iodide (PI) is a fluorescent dye that binds specifically to DNA, and passes through the damaged membrane attaching to the cell's DNA (Brito et al., 2003). The aim of this experiment is to investigate the correlation between these two tests and the possibility of performing them, conjugated, in the evaluation of the sperm membrane. The results demonstrated a positive correlation between HOST and PI fluorescence, supporting the results observed by other authors (Brito et al., 2003; Zúccari et al., 2009) and demonstrating the good efficiency of both tests. However, the HOST done from the fluorescence test, and the PI test performed ​​from HOST, showed significant differences regarding patterns tests. It is possible that centrifugation and TALP solution used for the semen wash on the fluorescent assay have altered the biochemical activities of the sperm membrane. The test with the probe made ​​from HOST might have been altered due to incubation time or presence of a diluting medium, interfering with the cells staining by PI. We conclude that some of the steps required in both assessments end up interfering with the results of the other test, thereby precluding the use of the conjugated techniques.