During the early years of the AIDS epidemic, youth born with perinatally acquired HIV (PHIV) were not expected to survive childhood. Today, they are living well into young adulthood, necessitating a transition from pediatric to adult infectious disease care. Previous research has emphasized the importance of disease-specific knowledge in preparing adolescents for a successful transition. Additional research has found that the quality of patient–provider relationships is associated with the intent to seek and continue care among adolescents. Among adults living with HIV, high-quality patient–provider interactions are related to improved medication adherence. The purpose of this study was to investigate the association between knowledge of disease markers (CD4 count and viral load) and quality of patient–provider interactions among 40 adolescents with PHIV (mean age 17.3 years), 90% of whom were African-American, with attention to implications for transition readiness. Twelve participants (30%) accurately defined what a CD4 count is, and only two participants accurately reported their own CD4 counts. Less than half of the participants correctly defined viral load, and only eight participants (20%) knew their own viral load. Seventeen participants (42.5%) answered all four questions incorrectly. All participants completed the Adolescent Patient Provider Interaction Scale, which indicated that the majority of adolescents experienced positive interactions with providers. Knowledge of disease markers was positively associated with patient–provider interaction. The significant association between disease marker knowledge and quality of patient–provider interactions suggests that adolescents with higher quality interactions with their providers possess greater knowledge about the disease and their own status. Poor understanding of HIV disease markers may adversely influence the transition to adult care. However, the strong patient–provider relationship offers a vehicle to promote increasing medical autonomy among adolescents, including understanding of important disease-related markers. [ABSTRACT FROM AUTHOR]