Introduction: We have used lenalidomide for 55 patients (pts) in relapsed and refractory myeloma setting since July 2010, of which 48 pts were treated with LD therapy. 36 pts were treated with LD therapy for more than one year from initiation of the therapy regardless of continuation or discontinuation of treatment, of which 16 pts have been treated continuously. We have analyzed the data of these 36 patients treated with LD therapy. Method: We define the duration of treatment as from the starting date of LD therapy to the last date of observation or discontinuation. We grouped LD therapy duration into two groups, short term therapy and long term therapy, for patients treated interrupted temporarily and for patients treated continuously over one year, respectively. The duration of treatment, gender, age, M protein type, ISS, D&S, renal dysfunction, efficacy, and overall survival(OS) are analyzed. Results: Male/female: 24/12, median age: 63(48-80), IgG/IgA/BJP: 22/11/3, ISSI/II/III: 12/15/9, D&SI/II/III: 0/12/24, median duration of treatment: 250.5days(7-968), response rate ≧ PR55.6%, CR5.6%, 2-year survival rate: 51.9%. The median OS for the long term therapy group was not reached compared with 317 days for the short term therapy group. Apparent correlations were observed between the duration of treatment and M protein type, efficacy, or OS. No significant correlations were obtained between the duration of treatment and gender, age, ISS, D&S, or renal dysfunction. Conclusion: Continuing LD therapy long has an impact on the extension of OS of myeloma patients.