Baseline and disease progression characteristics may predict the risk of skeletal-related events (SREs) in patients with bone metastases from various solid tumors. Exploratory analysis of phase III trials compared zoledronic acid with placebo in patients with bone metastases from castration-resistant prostate cancer (N = 643) and lung cancer or other solid tumors (N = 773), adjusted for baseline and time-dependent disease parameters. In all models, more than three bone lesions at baseline correlated with the increased SRE risk. Bone and overall disease progression correlated with increased SRE risk. Overall, cancer progression correlated with increased SRE risks and zoledronic acid was associated with reduced SRE risks versus placebo.