A method was described for determination of trace levels of silicon by inductively coupled plasma mass spectrometry (ICP-MS) from hydrofluoric (HF) digests of biological samples. The volatility of silicon in HF digests was examined with synthetic solutions as well as soil and mine waste samples. A digestion scheme was optimized to achieve complete dissolution, avoid loss of volatile silicon species and produce sample solutions that can be directly analyzed by ICP-MS. The performance of the method performance was validated by analysis of a number plant and tissue certified reference materials for silicon by ICP-MS. The method was then applied to the determination of silicon from lung biopsy tissues obtained from military personnel and coal miners.