Loss to follow-up (LTFU) in cancer patients is a serious problem, yet there is little data on this and on the underlying reasons. Of 144 paediatric and 431 adult patients with lymphoma diagnosed in 1997/1998 at King Faisal Specialist Hospital and Research Center, Riyadh (KFSHRC), 30% and 48.5%, respectively, were LTFU after 4 years (excluding patients known to have died). In 2001–2002, 196 paediatric and adult lymphoma patients at KFSHRC were enrolled in a prospective study in which explanations were obtained in detail for non-attendance at follow-up appointments (No Show). Sixteen months after commencement of the study, 49 patients were No Show, because of patient-based communication problems (20), transportation problems (8), patient not contactable (18), and personal reasons (3). In addition, patients were recorded incorrectly as No Show through hospital/patient communication problems. The No Show patients, especially the 23 who failed to keep a second appointment, are identifiable as potential LTFU during the 3 years in which this cohort will be followed. This study and, we suggest, other studies on LTFU should stimulate interest in this issue, in the predisposing factors, and in strategies to address them.