Gingivitis, dental caries, bacterial plaque, and the prevalence of Streptococcus mutans in plaque were studied in a group of 52 naval recruits from Saudi Arabia at the Naval Training Center, Great Lakes, Illinois. Gingivitis and bacterial plaque were found at higher levels in Arabian navy men, compared to American navy men, but with similar relationships. The dental caries experience of the Arabians was low, and the prevalence of S. mutans in the bacterial plaque had no clear relationship to gingival inflammation.