An investigation was conducted to test the hypothesis that age and wear of toothbrushes do not affect plaque removal. 40 preclinical dental students between the ages of 19 and 26 years were assigned randomly to 2 groups. 1 group of 19 subjects used a toothbrush for 10 weeks while the 21 subjects in the other group were given new toothbrushes every 2 weeks for 10 weeks. A baseline of zero plaque and calculus was obtained on the first visit. On subsequent visits, 2 weeks apart, the gingival status of each group was evaluated using the gingival index, and plaque levels were scored using the patient hygiene performance index. The brushing surface area of the toothbrushes was measured with a caliper as well as being graded subjectively according to their condition (good, fair or poor). Results were statistically analysed at the end of the 10-week period. It was found that after 10 weeks, the subjects using the same toothbrush for the whole period had significantly more plaque than those who replaced their brushes every 2 weeks. As brushes deteriorated, they became less effective. No differences in gingival state were detected. There was appreciable variation in toothbrush wear among subjects, some reducing their brush to a poor state in 2 weeks whereas with others the brush was rated as "good" after 10 weeks.