Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been increasingly used in routine clinical laboratories during the last two decades. The high specificity, sensitivity, and multi-analyte potential make it an ideal alternative to immunoassays or conventional high-performance liquid chromatography (HPLC). It also provides higher throughput than gas chromatography-mass spectrometry (GC-MS). LC-MS/MS also offers higher flexibility than immunoassays because LC-MS/MS assays are typically developed in-house. In addition, abundant information can be obtained from a single LC-MS/MS run which can produce a large amount of quantitative or qualitative data. In this review, typical LC-MS/MS clinical applications are presented, personal experiences are shared, and strengths and weakness are discussed. It is foreseeable that LC-MS/MS will become a key instrument in routine clinical laboratories.