Pathogens affect the evolution of their hosts only to the extent that the host's ability to reproduce is altered. Microbotryum violaceum is a pollinator-transmitted fungal pathogen that causes infected individuals to produce sterile flowers with anthers full of fungal spores. In North American Rocky Mountain populations of Silene acaulis, a host to M. violaceum, reproduction in infected individuals is severely affected, but disease spread is slow (Ͻ1% new infections over a 4-yr period). This study addresses whether diseased plants can affect reproduction in healthy individuals even if the healthy plant does not become diseased. I studied Silene acaulis in the field to examine traits of diseased and healthy plants, pollen deposition, spore deposition, and seed production in healthy plants. Diseased plants were significantly larger than healthy plants, and in contrast to other studies of anther smut with different hosts, infected individuals did not produce more flowers than healthy individuals. Timing of flowering was similar for healthy and diseased plants, but peak deposition of pollen and fungal spores differed at some sites. Therefore, plants could potentially maximize their fitness by flowering at times of peak deposition of pollen while avoiding exposure to peak deposition of fungal spores. Finally, healthy flowers receiving additions of pollen and moderate to high loads of fungal spores produced significantly less seed compared to flowers receiving only pollen. Although the risk of becoming diseased may be low in this population, healthy individuals can be affected by anther smut because the majority of flowers receive fungal spores, which may be interfering with pollen grains and reducing seed production.