Oral hygiene behavior was surveyed in June 1971 by interviews with a sample comprising 1063 persons drawn to cover the total Finnish population aged 15 years and over. The interview revealed that the frequency of brushing as reported by dentulous interviewees was distributed as follows: less than once a day (32%), once a day (25%) and more than once a day (43%). Six percent of the interviewees stated that they did not brush their teeth. Most commonly the brushing was performed either as the last thing before retiring for the night (67%) or immediately after waking up in the morning (47%). There was a strong positive correlation between high socioeconomic status and high frequency of toothbrushing. Freshening of the breath and mouth was the most common (55%) reason for brushing the teeth and forgetfulness was the most frequent reason for neglecting it (56%). The investigation showed tha the dental health behavior of the Finnish people with respect to brushing of the teeth has much room for improvement.