OBJECTIVE: This study analyses the correlation between the Swedish underprivileged area score and sales of tranquillizers, hypnotics/sedatives, neuroleptics and antidepressants, and the correlation between these sales and mortality and suicide rates, with the aim of using sales data to identify areas with poor socioeconomic conditions. SETTING: Southern Sweden, 33 municipalities in Skåne, 1987 and 1994. DESIGN: Ecological study. Determined and undetermined cases of suicide were taken from the local death register for the years 1987-1993. Suicide rates (determined and undetermined cases) were calculated as the ratio between observed and expected number of suicides. Mortality for people aged 20-64 years was calculated from life tables for the decade 1981-1990. The underprivileged area score was calculated for municipalities using the proportion of persons in the following groups: elderly living alone, under 5 years of age, one-parent families, unskilled, unemployed, living in crowded households, those moving house in the previous year, and ethnic groups. After transformation (square root of arc sine) and standardization, each of the eight variables was weighted by the British general practitioners average weighting and added to give the underprivileged area score. The selection of the eight variables was based on general practitioners' perceptions of the effect of the social characteristics of the populations in their respective residential areas on their workload or pressure on services. The total drug sales figures for tranquillizers, hypnotics/sedatives, neuroleptics and antidepressants are expressed in Defined Daily Doses per 1000 inhabitants per day. The relationship between these variables was analysed using Pearson's correlation coefficient. RESULTS: There was a moderate correlation (0.41-0.68) between the sales expressed as in Defined Daily Doses per 1000 inhabitants per day of tranquillizers and hypnotics/sedatives and underprivileged area score. Furthermore, the sales of tranquillizers and hypnotics/sedatives seemed to be moderately correlated with both mortality (0.44-0.67) and suicide (0.47-0.58). CONCLUSION: Sales of tranquillizers or hypnotics/sedatives could be used with caution as markers for socioeconomic conditions on the basis of their moderate ecological correlation with a composite socioeconomic index such as the Swedish underprivileged area score and their moderate correlation with mortality and suicide.