BackgroundAccess to research volunteers may be hampered by low numbers of cases and few eligible participants for rare diseases in clinical settings.MethodsWe recruited volunteers and obtained informed consent by mail from narcolepsy cases in a case-control study, and here in we report feasibility, response rate, timeliness and cost. We invited index cases into the study by mail through their care-giving physicians then mailed study information and consent forms to cases that indicated interest in the study.ResultsOf the 33 index cases invited, (...) 15 expressed interest in the study, and of those, 14 returned their signed informed consents by mail. The median number of days from invitation to consent return was 39, interquartile range = 45, and the cost per consent obtained from the recruited subjects was $ 23.61.ConclusionIn this setting, postal recruitment for biomedical research on rare conditions is feasible and time and cost effective. (shrink)