Typically, luminol is preferred over other reagents in presumptive testing to identify bloodstains only in those cases in which the stain cannot be seen with the naked eye. The current study found, however, that the detection limit for luminol and the possibility of obtaining a false negative result on a bloodstain were significantly lower for luminol when compared with the reagents of o-tolidine, phenolphthalein, or any other reagent based on similar oxidation/reduction mechanisms. It has also been customary to undertake a second confirmation test when using luminol. This procedure should be reconsidered, given that luminol has been found to be more sensitive than other reagents and presents less interference. A confirmation test only makes sense when a more reliable procedure is used in the confirmation test. The Material Safety Data Sheets for o-tolidine and phenolphthalein, as well as for other reagent components, have more severe warnings than those for luminol. Another advantage of luminol is that because of the peculiar nature of its reaction mechanism, the test can be repeated various times, which cannot be done with other tests. The article concludes that there is no reason why luminol, as a unique detection method for invisible bloodstains, should not be given the status of a first-choice test when establishing the hematological nature of a stain. 3 tables and 21 references