Many tests for pollen viability have been proposed. The ability to determine this reproductive state in the field can be very important in botanical research as well as for horticultural purposes. After reviewing a large number of tests, we compared four methods of determining pollen viability. Each of these methods can easily be carried out in the field. Viability tests were carried out on 17 species from Israel and were compared to in vitro germination trials. No one test worked well on all species. The MTT stain was determined as the most effective for a wide number of species, but tests for individual species should be conducted before final determinations are made.