ONE HUNDRED FOUR adult subjects (mean age 42.8 years, SD = 16.3 years) with unilateral open contacts were assessed interproximally for periodontal status at both the open and contralateral closed contact. An open contact was defined by unrestricted passage of unwaxed dental floss through the interproximal area. Gingival index, crevicular bleeding, probing depth, attachment level, debris, calculus and tendency for food impaction in each study area were recorded. Less debris was seen at open contacts (P less than 0.001). However, increased probing depth (0.27 mm, P = 0.002) and attachment loss (0.48 mm, P less than 0.001) were found at the open contacts. Small but statistically significant relationships were observed between side to side differences in food impaction and both probing depth (P = 0.005) and attachment level (P = 0.006). Differences in calculus index and attachment level were associated similarly (P = 0.003).