AIMS AND OBJECTIVES: To describe the family-related characteristics of young adults with sickle-cell disease or sickle-cell trait prior to taking part in a randomised controlled trial on sickle-cell reproductive health education. BACKGROUND: There is a critical need for educational programmes that target the reproductive needs of young adults with sickle-cell disease or trait. However, little is known about the family-related characteristics (i.e., demographic attributes and reproductive health behaviours) in which these young adults live. DESIGN: A descriptive cross-sectional analysis. METHOD: At study enrolment, 234 young adults (mean age = 25.9 years, 65% female) completed the SCKnowIQ questionnaire. Descriptive statistics depict the demographic attributes and reproductive health behaviours of young adults with sickle-cell disease (n = 138) or trait (n = 96). For group comparisons, independent t tests or Fisher's tests were used, as appropriate. RESULTS: Young adults with sickle-cell trait had significantly higher education, income and health insurance than those with sickle-cell disease. Both groups believed that sickle-cell disease was a severe condition. A majority of young adults with sickle-cell disease (65%) had no children compared to 42% of those with sickle-cell trait. Most young adults (85% sickle-cell disease, 82% sickle-cell trait) were not planning a pregnancy in the next six months, and many used condoms, withdrawal or oral contraceptives. CONCLUSIONS: Socioeconomic disparities exist between young adults with sickle-cell disease and sickle-cell trait. Future research that advances education about how and when to communicate appropriate genetic risk information to partners and children especially for young adults with sickle-cell trait would be beneficial. RELEVANCE TO CLINICAL PRACTICE: Awareness of the similarities and differences in the family-related characteristics among young adults with sickle-cell disease or trait can allow for more tailored reproductive education.