OBJECTIVES: Attachment style, or ability to be self-reliant and trust others, categorized as secure, preoccupied, dismissing or fearful, is related to health outcomes.  Individuals successfully seeking social support can better cope with negative events.   The attachment style of gay men may affect their ability to be public about their sexual orientation and seek support, which could affect their health-related quality of life (HRQOL).  We assessed variation in the attachment style of gay men with prostate cancer and its relationship with HRQOL.  METHODS: Participants (N=91) were from a convenience sample of gay men with localized prostate cancer.  HRQOL was measured using the Short Form-36 (SF-36) (v1.0) and the Expanded Prostate Cancer Index Composite (EPIC); the attachment style was scored using the Relationship Questionnaire. Differences in attachment style were assessed using ANOVA.  Multiple regression models were run to predict the SF-36 physical (PCS) or mental (MCS) components.   RESULTS: Individuals with dismissing attachment style had lower social network scores and indicated higher bowel symptom bother, though their bowel function was higher than that of fearful individuals (p<0.05).  Dismissing individuals were more comfortable being public about their sexual orientation than preoccupied individuals; had a higher MCS, but did not differ on PCS than fearful individuals. After adjusting for demographics, social support, especially size of social network, predicted the MCS; while bowel functioning, urinary/sexual bother, and comfort with being public about their sexual orientation predicted the PCS on the SF-36 (p<0.05).  CONCLUSIONS:   Social network may vary by attachment style, affecting psychosocial adjustment.  Interventions should use attachment style as a marker for limited social support and poor long-term HRQOL to identify gay men with prostate cancer needing additional assistance.