Abstract Following the January 17, 1994, Northridge, California, earthquake (M = 6.7), Ventura County, California, experienced a major outbreak of coccidioidomycosis (valley fever), a respiratory disease contracted by inhaling airborne fungal spores. In the eight weeks following the earthquake (January 24 through March 15), 203 outbreak-associated cases were reported, which is about an order of magnitude more than the expected number of cases, and 3 of these cases were fatal. Simi Valley, in easternmost Ventura County, had the highest attack rate in the county, and the attack rate decreased westward across the county. The temporal and spatial distribution of coccidioidomycosis cases indicates that the outbreak resulted from inhalation of spore-contaminated dust generated by earthquake-triggered landslides. Canyons northeast of Simi Valley produced many highly disrupted, dust-generating landslides during the earthquake and its aftershocks. Prevailing winds after the earthquake were from the northeast, which transported dust into Simi Valley and beyond to communities to the west. The 3 fatalities from the coccidioidomycosis epidemic accounted for 4% of the total earthquake-related fatalities.