The aim of the present study was to determine the motivational effect of using a periodontal self-examination manual prior to a self-instructional manual in oral hygiene and to examine whether instruction provided at a later time than the scaling procedure improves the effect of the instruction. 74 patients with periodontal disease were divided into 3 groups: (1) A group of 23 patients who performed a self-examination of their periodontal condition prior to self-instruction in oral hygiene; (2) a control group of 27 patients who used only the self-instructional oral hygiene manual; and (3) a group of 24 patients who were not given the self-instructional oral hygiene manual before 6 weeks after the baseline examination. All these patients had their teeth scaled at the start of the study and after 3 and 7 months. The effect of the various modes of instruction was evaluated by assessments of plaque and gingival bleeding scores. These parameters were determined at the baseline and after 2 and 6 weeks and 3 and 7 months. The results demonstrated a significant improvement in plaque and gingival bleeding scores following the use of the self-instructional manual in oral hygiene. The use of the periodontal self-examination manual or a delay of the instruction had no additional effect on oral cleanliness. The level of oral hygiene and gingival health achieved at 3 months was maintained in all 3 groups for an additional period of 4 months. After that time, they were divided into 2 other groups depending on whether or not their plaque score was less than 20%. A total of 26 in the group who had a plaque score higher than 20% demonstrated a plaque score of than 20% after having performed the tooth brushing test. 10 of the remaining patients, who still had a plaque score of more than 20% after the tooth brushing test, received additional instruction in oral hygiene which subsequently resulted in improved oral cleanliness after 6 months.