The objective of this research was to characterize the in vitro cellular behavior of fibroblast-like cells derived from rat periodontal ligament on commercially pure titanium surfaces which were sterilized by a variety of treatments. Following standard surface preparation protocols, the Ti specimens were sterilized by either steam autoclaving, exposure to ethylene oxide gas, exposure to ultraviolet light, or plasma-cleaning in argon for either one min or five min. Fibroblast-like cells in serum-supplemented media were incubated on the various Ti specimens for up to two h. In general, the levels of cell attachment for plasma-cleaned surfaces were significantly higher than those for steam-sterilized surfaces, but were significantly lower than the attachment levels for both the ultraviolet-treated surfaces and the tissue culture plastic control. The duration of plasma cleaning itself did not have a significant effect on the percentage of cell attachment at any time period. SEM evaluations indicated that by two h, the cellular morphology was different on the variously treated specimens. These studies indicate that the method of sterilization following implant surface preparation can affect the initial in vitro biological events of cell attachment and spreading.