The work presents a brief historical review of tandem mass spectrometry (MS-MS), indicating a vast progress in the field during the last decade. Instrumentation aspects are touched while describing basic principles of operation as well as analytical characteristics of the most popular tandems. Various applications of MS-MS in the filed of life science are overviewed, including drug discovery and proteomics. The review is mostly concerned with  the logics of the field evolution and a mutual relation between instrumentation and applications. Recent advances in tandem mass spectrometry as well as revolutional leap in bioinformatics has made MS-MS the most specific and the most sensitive tool and a tool of choice for biochemical analysis.  In return, life science became the major customer and a very noticeable driving force in the instrumentation development. The review highlights the fact that life science deals with very complex mixtures containing up to 10**6 components in a wide dynamic range of concentrations, up to 10**6. The nature of biochemical problems requires even higher sensitivity, specificity and throughput of MS-MS, and its compatibility with a wide range of separation tools, which is likely to cause further dramatic changes in MS-MS instrumentation.