BACKGROUND: The active ingredients of marijuana may have beneficial properties in the treatment of chronic pain and inflammation and is being used by sufferers of chronic pain and arthritis in some settings. Anecdotally, marijuana is believed by some sickle cell disease (SCD) patients to improve their health. This study aimed to determine the prevalence of marijuana smoking in the Jamaica Sickle Cell Cohort Study (JSCCS) in the years 2000 and 2004. The perception that marijuana use ameliorated the complications of SCD was also investigated. METHODS: All patients in the JSCCS were invited to attend an annual review, and during the 2000 and 2004 reviews, participants with homozygous sickle cell (SS) disease and sickle cell haemoglobin-C (SC) disease were asked whether they smoked marijuana, and if they smoked, whether it was used for medicinal purposes related to SCD. The authors compared smoking prevalence by gender, disease, and year of review. The association of smoking with a measure of pain frequency was also examined. RESULTS: The prevalence of marijuana smoking was higher among men and among SC participants. The proportion of either gender reporting smoking of marijuana increased in 2004 compared to 2000, and this use was not related to a simple measure of clinical severity of SCD. CONCLUSIONS: Marijuana smoking is common in adults with SCD but its usage is unrelated to clinical severity of the disease.