A detailed investigation of trends in suicide rates in Scotland from 1974 to 1984 showed a complex pattern. Overall rates for men increased by 40% with the greatest increases in those aged 45-64. In contrast, rates for women showed a small decline, which was most noticeable in those aged 15-24. The well recognised decline in poisoning by domestic gas was seen over this period, and suicide by this method virtually stopped. Both sexes showed a decline in suicide by poisoning with drugs, although the decrease was larger among women. The fall in suicide rates among young women was almost all due to the decrease in this method. The rise in rates for men was largely due to increases in hanging and poisoning with vehicle exhaust gases, although all methods except drugs and domestic gas showed some increase. These findings indicate that suicide is an increasing problem with causes that are far from understood, so that prevention may be difficult.