HIV serostatus disclosure is a crucial decision, and often perceived as a double-edged sword for people living with HIV. This study was intended to determine the extent of disclosure according to interpersonal relationships, compare the characteristics of disclosure by modes of HIV transmission, and to describe perceived consequences after disclosure to Taiwanese families. Data were collected by in-depth interviews and chart reviews at HIV primary care clinics in a university hospital in southern Taiwan from 2004 to 2005. Of 105 male participants interviewed, 76 (72.4%) had disclosed their HIV status to at least one person, including 62% to an immediate family member and 21% to friends. The HIV disclosure rates were different in three groups divided by modes of transmission, 36% in men having sex with men (MSM), 34% in heterosexuals, and 21% in injection drug users (IDUs). MSM were more likely than heterosexual men or male IDUs to disclose their HIV status directly to friends immediately after leaning of their HIV diagnosis. Heterosexual men and male injection drug users often disclosed to their immediate families a few days after obtaining an HIV diagnosis. Perceived consequences after disclosure included: increased substantial support from family, assistance with medical and healthcare, encouragement of living positively with HIV, being rejected, treated as contagion, and condemnation. Disclosure of HIV-positive status in a family-oriented Taiwanese society is a complex process and different by the modes of transmission.