Needle-use practices of intravenous drug users (IVDUs) were examined in a region (Seattle, King County, Washington State, USA) where needle purchase is legal. IVDUs in treatment (n = 313) were administered extensive structured interviews concerning drug and injection equipment-use practices. Of the 80.2% reporting intravenous drug use in the previous year, 78.3% reported sharing needles. Of the 47.7% reporting intravenous use in the previous 30 days, only 40.5% shared needles, with 59.3% sharing with only one other person. Most needle-sharing partners were very well known (63%) or well known (17%) to the subjects. The most frequent method for obtaining needles was 'buying in a drug store', ranked first by 65% of the sample. Subjects whose primary source was 'buying in a drug store' shared equipment less frequently during drug-use events in the previous year (mean: 16.2%) than those with other primary sources (mean: 28.5%). Compared with findings from other regions where needle purchase and possession are illegal without a prescription, fewer subjects in the current investigation shared needles, and those who did shared with a smaller number of people. The apparent association between legalized injection equipment and reduced sharing of equipment among IVDUs should be further examined in longitudinal studies of needle-sharing before and after legalization is instituted.