​The impacts of UV-B radiation to Red Sea coastal zooplankton was assessed experimentally at the time (May/June) of peak UV-B radiation, using the most abundant zooplankton species in the community (eight copepod genera, a cladoceran, an ostracod, a cumacean, and two meroplankton, including crab zoeae and megalopa). Mortality rates increased greatly in the presence of ambient UV-B radiation for all species tested except for Labidocera, Macrosetella, and the crab megalopa larvae. Mortality rates declined, on average, threefold when UV-B radiation was removed. These results provide evidence that Red Sea zooplankton are highly vulnerable to ambient levels of UV-B radiation.