<p dir="ltr"><i>Beauveria bassiana</i> is an insect pathogenic fungus that has also been found to grow within plant tissues (i.e., endophytically) of many important crops such as maize. However, the effect on plant growth metrics and the pattern of colonization within maize is not well characterized. This research used two strains of <i>B. bassiana</i>, GHA and MA20, and measured the capacity of these strains to grown endophytically in maize and the effects on growth of maize plants. These data include results from experiments measuring the presence versus absence of <i>B. bassiana</i> growing endophytically in roots, stem, and leaf tissue of maize, in addition to data on the abundance of <i>B. bassiana</i> in the growth substrate. This data set also contains results from experiments testing the effect of <i>B. bassiana</i> on the growth of maize plants through measurements of plant metrics, including height, basal stem diameter, and plant biomass. The data are presented across two csv. files.</p>