The effect of using a television-tape demonstration in order to reinforce the advice given in a self-teaching oral hygiene program was evaluated in the present study. The teeth of 24 periodontal patients were scaled and 2 weeks later oral hygiene instruction was given by handing out a self-teaching manual. The patients were divided into 2 groups, matched with regard to the initial status of oral cleanliness. (1) An experimental group (TV) comprising 12 patients who, 1 week after the instruction, were shown a demonstration of proper oral hygiene technique on closed circuit television and (2) a control group of 12 patients who did not receive this reinforcement. The presence or absence of dento-gingival plaque and gingival bleeding by gentle probing was recorded initially and after 8 weeks on 4 surfaces of all teeth. In addition, plaque scores were recorded at 2 and 3 weeks to assess the effect of the oral hygiene self-instruction. At the final examination after 8 weeks, the patients with plaque on more than 20% of the tooth surfaces were subjected to a tooth cleaning test including a subsequent scoring of remaining plaque. The patients that the experimental group (TV) were asked their opinion regarding the television-tape demonstration. Although the patients in the experimental group expressed a positive opinion about viewing the television-tape demonstration, the improvement in the plaque and gingival bleeding scores recorded at the 8-week examination showed no difference between the 2 groups of patients. Similarly, the scoring of plaque after the tooth cleaning test showed no difference between the 2 groups. Only 5 (20%) out of the 24 patients were unable to clean their teeth to a standard of less than 20% plaque-infected tooth surfaces.