Nuclear magnetic resonance (NMR) experiments on macromolecules can generate a tremendous amount of data that must be analyzed and correlated to generate conclusions about the structure and dynamics of the molecular system. NMRView is a computer program that is designed to be useful in visualizing and analyzing these data. NMRView works with various types of NMR datasets and can have multiple datasets and display windows opened simultaneously. Virtually all actions of the program can be controlled through the Tcl scripting language, and new graphical user interface components can be added with the Tk toolkit. NMR spectral peaks can be analyzed and assigned. A suite of tools exists within NMRView for assigning the data from triple-resonance experiments.