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Fire line construction using a bladed implement such as a bull dozer breaks fuel continuity and stops the spread of fire by removing vegetation. Because bladed fire lines can alter subsequent vegetation, these changes may be more significant than the impact of the fire itself, however relatively little research has been performed to evaluate this potential. In this study we compared vegetation attributes among burned, unburned, and bladed fire line conditions on two fires that burned in late summer 2012, one in north-central Montana and one in southwest Montana. Vegetation cover and standing biomass were quantified in 2013 and comparisons between treatments made using analysis of variance with significance evaluated at ? = 0.05. Fire line construction generated a significant decrease in perennial grass cover and biomass and an increase in annual grass and annual forb cover and biomass. Burning did not cause a change in vegetation relative to the unburned treatment with the exception of a reduction in litter biomass. Our data show a significant reduction in vegetation abundance and suggest the potential for conversion to an annual grass dominated system in association with fire line construction. This is concerning because the dominant annual grass was Bromus tectorum which has the ability to permanently degrade ecosystem function. Although longer term data are required to more fully understand how these fire lines recover, our data suggests a need to consider the impacts of unplanned bladed fire line construction particularly in situations where other high value entities are not in jeopardy.