The benefit obtained from the use of a manual for self-assessment of gingival bleeding was evaluated among a group of Finnish army conscripts. After the baseline examination, performed by a dentist, three test groups self-assessed bleeding from their gums during toothbrushing and when cleaning between their teeth with a toothpick. The dentist re-examined the first test group 1 month, the second group 3 months and the third group 6 months after the self-assessment. Gingival bleeding among the test group subjects was compared with that of control group subjects who had been matched for number of bleeding sites at baseline. The self-assessed gingival bleeding was found to correlate with the clinical findings of bleeding. One and 3 months after the self-assessment the test groups had better gingival health than their respective control groups. Six months after the self-assessment, no difference in gingival health was found between the test and control groups. Observed gingival bleeding during the original self-assessment was found to be a positive predictive factor for the subsequent improvement in gingival health.