Existing SAM visualization tools like samtools tview (Li et al., 2009) are limited to a small region of the genome, and tools like Tablet (Milne et al., 2010) are limited to a relatively small number of reads and may fail outright on large datasets. We need to visualize complex ChIP-Seq and RNA-Seq features such as polarity as well as coverage across whole 3 Gbp genomes such as Human. We have addressed these problems in a lightweight visualization system called SAMSCOPE accelerated by OpenGL. The extensive pre-processing and fast OpenGL interface of SAMSCOPE provides instantaneous and intuitive browsing of complex data at all levels of detail across multiple experiments.