Mesoptometer Model I (Oculus) and Nyktometer (Rodenstock) were compared monocularly in 328 eyes. The individual measurements varied widely, more so for mesopic vision with dazzle than for mesopic vision without dazzle. When the results were classified in accordance with the normal limits proposed by the German Ophthalmological Society there was good correlation between the two instruments. The results fell into the same category in about 85% of the cases.