From August 3 until August 5, 1965, a heavy concentration of dust and some sulphurous fumes were noted in the Valley of 10, 000 Smokes and the Brooks River area of Katmai National Monument, Alaska. Visual and seismic observations during July and August indicated that although there was no major volcanic eruption, there was a slight increase of seismic activity in late July near Mt. Trident and in early August near Mt. Martin. Observations of volcanic activity, however, in the Katmai region during 1965, were inadequate to relate volcanic and seismic events. While an aeolian origin for the observed dust and fumes can not be ruled out, some type of volcanic activity seems likely.