OBJECTIVES: The aim of this prospective, observational, multicenter study was to estimate the management costs of bone metastatic disease (BMD) in patients with lung cancer. METHODS: Consecutive patients presenting BMD from lung cancer diagnosed between May 2006 and May 2007 in 40 centers were enrolled. The natural course of bone metastatic disease was modeled using a Markov model with 4 health states (asymptomatic patient, symptomatic patient, skeletal-related event (SRE) and death) and a cycle length of one month, until death or a 5-year period. Direct medical costs induced by BMD (including symptomatic or therapeutic treatment and hospitalizations) were prospectively collected from the health care provider's perspective. RESULTS: Among the 554 patients enrolled (mean age 62 years, 77% of males), 26.7% presented a SRE at diagnosis and 39% during follow-up. The median survival time was 5.8 months, and the 1- and 2-year survival rates were 22% and 7%, respectively. The main BMD treatments were opiate therapy (78%), biphosphonates (52%), radiotherapy (42%), and surgery (9%). The mean monthly BMD treatment costs were 190 €, 374 €, and 4 672 € for asymptomatic patients, symptomatic patients, and patients with SRE, respectively. The average first-year BMD management cost was 3 999 € ± 4 135 (IC95%: 374-15 886), and 49.5% of this cost was attributable to patients with SRE. CONCLUSIONS: This analysis underlines the burden of bone metastatic disease, and particularly of skeletal-related event in overall treatment costs.