The objective of this study was to ascertain the relationship among intravenous drug users between high levels of HIV risk-taking and both (a) deaths of significant others experienced before age 15, and (b) unresolved mourning; 592 out-of-treatment intravenous drug users (71.4% male; mean age = 40.5), stratified as to zip code, were recruited in San Jose, CA, as part of a CDC multisite investigation of access to sterile needles and HIV infection. HIV serostatus tests were obtained and an individual, structured interview administered covering demographics, employment, mental health, HIV risk-taking behavior, family contacts/closeness, and family deaths/mourning. Multivariate analyses indicated that the extent of HIV risk-taking in adulthood was highly and positively related to (a) the number of close-family-member deaths participants experienced as youth, (b) the extent to which respondents effectively mourned sudden family losses, (c) the extent to which those lost were emotionally close to the respondent, and (d) whether or not the respondent attended the funerals of lost relatives. Canonical correlations between sets of death/mourning and HIV risk-taking variables were .55 for the total sample (p < .001) and .70 for the subsample who experienced early and sudden family deaths (p < .001). In both analyses, it made little difference if age and gender were partialed out. These findings give credence to the importance of (a) unexpected deaths experienced early in life, and (b) related, inadequate mourning, as factors in progressively higher adult HIV risk-taking. They suggest that treatment for such individuals and their families should involve grief work dealing with unresolved losses within the family of origin. In addition, prevention efforts may have to revise their modus operandi toward both more focused and more family-based methods of outreach and engagement.