Carriage or infection with penicillin-non-susceptible Streptococcus pneumoniae (PNSP) has been associated with antibiotic prescribing, socioeconomic factors, and attendance at day-care centres (DCCs). In the present study, linear regression was used to estimate the relation between these risk factors and the incidence of PNSP cases (non-susceptible defined as MIC =0.5 microg/ml for penicillin) in 19 residential areas in Malmö. The number of PNSP cases was associated with the number of preschool children in the area (r=0.950, p<0.0001). The incidence of PNSP cases per 1000 children was positively correlated with antibiotic prescribing (r=0.614, p<0.01) but not with DCC attendance or any of the socioeconomic factors studied. Antibiotic prescribing was, however, positively correlated with per capita income (r = 0.597, p<0.05). Thus, even if higher socioeconomic status alone had no apparent influence on the incidence of PNSP in Malmö, there was still an indirect relation between these 2 factors, since inhabitants in these areas consumed more antibiotics. Based on these results, the spread of antibiotic-resistant pneumococci seems to be most reliably restricted by pursuing a restrictive policy regarding antibiotic prescription.