Antiretroviral treatment dramatically reduces mortality and prolongs the life expectancy of HIV/AIDS patients in Taiwan. The stigma attached to AIDS, and conflicts within the family result in family stress and emotional distress. Consequently, parents of adult children with HIV/AIDS endure perpetual distress while caring for their adult children. The purpose of this study is to elucidate the experiences of seven parents caring for children over 18 years of age with HIV/AIDS. Hermeneutic phenomenological methodology was applied to reveal the trajectory of parents' caring experiences and to discover the hidden meanings of the phenomena. Data were collected using semi-structured in-depth interviews lasting from 1.5 to three hours. Interviews were tape-recorded and transcribed verbatim. Data were analyzed using thematic analysis with the concept of the hermeneutic circle. Four essential themes emerged, and were identified and clarified. The parents' caring experiences were: (1) We didn't expect our children's controversial illness, so we pretend to ignore the taboo; (2) We are suffering from shame, and our daily lives and interaction with others have changed; (3) We provide advice frequently to protect our children from pain, and try our best to take care of them in order to bring them better fortune; and (4) We feel helpless in the face of predestined causality, and wish we could bear the burden of sin for our children. Unconditional love and endless responsibility, furthermore, were the essential experiences of these parents. Our findings highlight the importance of patient-center nursing care for HIV/AIDS patients and for healthcare professionals to assist HIV affected families on related family stress throughout the illness trajectory.