We investigated the effect of nitrazepam on nocturnal scratching in 10 adult out-patients with atopic dermatitis (AD) using a double-blind placebo-controlled crossover method. Patients were given either nitrazepam (Benzalin tablets containing 5 mg nitrazepam) or a placebo on 3 successive nights, with a washout interval of 4 days. We used an infrared video camera to identify bouts of scratching lasting more than 5 s. These were counted and the duration of all the bouts of scratching (total scratching time, TST) was calculated. The percentage of TST to total recording time (TST%) was used as an index of nocturnal scratching. The frequency with which bouts of scratching (bouts/h) occurred was reduced by 10 mg nitrazepam (7.7 +/- 3.6 with nitrazepam vs. 9.6 +/- 3.6 with placebo, P < 0.05). However, the mean duration (s/bout) of the bouts of scratching was longer with 10 mg nitrazepam (32.3 +/- 23.4 with nitrazepam vs. 19.1 +/- 10.0 with placebo, P < 0.05). As a result, there was no significant difference between TST% (6.5 +/- 4.2 with nitrazepam vs. 5.4 +/- 3.8 with placebo, not significant). All the above values are mean +/- SD. The degree of itching and the condition of the AD did not change during the 2 weeks of the study. We conclude that taking 10 mg nitrazepam is not an effective way of reducing the total duration of nocturnal scratching in AD patients, although it decreases the frequency with which bouts of nocturnal scratching occur.