Leptomeningeal involvement in patients with CLL is relatively rare and the prognosis is usually considered to be poor. The authors reviewed all CLL patients treated in a tertiary referral center to assess the incidence and outcome of leptomeningeal involvement (LI) in CLL. They found an incidence of 1-2% of LI. Most of the patients with LI had a long-term survival, despite failure to clear the cerebrospinal fluid from tumor cells