Nanoparticle technology refers to research and technology developed at the atomic or molecular level for materials of approximately 1-100 nm in length. Through accidental or involuntary exposure, nanoparticles are potentially toxic to the body, including reproductive organs. Ovarian granulosa cells play a major role in maintaining ovarian function, health, and female fertility. Since these cells are involved in steroidogenesis, we wished to evaluate whether nanoparticles affected them after traversing their membranes. Cells were co-incubated with 10 nm gold particles for up to 24 h. Transmission electron micrographs were taken of GC treated with 10 nm gold particles in order to compare and contrast ultrastructural locations of nanoparticles with treatment. From micrograph comparisons of treated vs. untreated GC at various culture times, it appeared that some intracellular organelles involved in steroidogenesis were infiltrated and/or altered due to the presence of the nanogold particles. Medium samples were taken in order to determine estradiol-17beta (E2) accumulation/secretion by untreated vs. treated cells. GC incubated with 10 nm nanogold particles for 1, 3, or 5 h were found to accumulate significantly increased amounts of estrogen compared with untreated cells. Conversely, at 24 h there was a significant attenuation with respect to controls. The data presented here provide insight into the toxicologic effects gold nanoparticles elicit on ovarian granulosa cells.