Failing implants with loss of alveolar bone are associated with gram-negative bacteria that carry lipopolysaccharide (LPS) in the bacterial cell wall. Bony regeneration around these implants is still an unpredictable procedure due to the many clinical factors involved. One important factor is the presence of contaminants such as LPS on the implant surface. The effect of implant-associated LPS on the attachment of bone cells to the implant surface is unknown. This project investigated the effect of LPS on the attachment of osteoblast-like cells (MC3T3-E1) to titanium and titanium alloy surfaces in vitro. We hypothesized that LPS would inhibit bone cell attachment either through loss of cellular attachment sites or alteration of cellular function. Three experimental approaches were used. First, alloy surfaces were exposed to LPS (100 μg/mL) before the cells were allowed to attach. In the second approach, the cells were exposed to the LPS before they were allowed to attach. Last, the cells were allowed to attach before exposure to LPS. Cellular attachment to implant materials was measured by using a histochemical stain (MTT). The results indicated that LPS presence did not significantly (P > .05) alter osteoblast attachment to titanium or titanium alloy surfaces whether the exposure occurred before or after cellular adherence. It was concluded that LPS did not directly effect the attachment of the MC3T3-E1 osteoblasts to these implant surfaces in vitro. Further research is needed to define the clinical liabilities of LPS during implant placement and maintenance.