A key issue in the debate on suicide prevention is the extent to which suicide rates are affected by the availability of means of committing suicide. The aim of this study was to analyse the changes in rates of suicides committed by poisoning in Sweden between 1969 and 1992, and to determine to what extent these were associated with changes in the prescribing of medicines. We compared suicide rates from 1969 to 1992 with trends in the sales of antidepressants, barbiturates, neuroleptics and analgesics during the same period. The incidence of suicide by poisoning decreased during the 1970s, especially in younger and middle-aged men. This was mainly due to a decrease in suicides by barbiturate poisoning, which closely followed a decrease in sales of barbiturates. Sales of analgesics and antidepressants increased during the study period, and so did the rates of suicide using these drugs. We conclude that the availability of medicines is an important factor influencing suicide rates, and that changes in the prescribing of medicines may influence suicide rates.