Analytic methods are continuing to be developed and applied using the GELLAB-II software system - an exploratory data analysis system for the analysis of sets of 2D electrophoretic gel images. It incorporates sophisticated subsystems for image acquisition, processing, database manipulation, graphics and statistical analysis. It has been applied to a variety of experimental systems in which quantitative and qualitative changes in one or more proteins among hundreds or thousands of unaltered proteins is the basic analytic problem. Keeping track of changes detected using these methods is also a major attribute of the system. A composite gel database may be """"""""viewed"""""""" under different exploratory data analysis conditions and statistical differences and subtle patterns elucidated from """"""""slices"""""""" of an effectively 3D database. Results can be presented in a variety of tables, plots or derived images and on workstations over wide area networks. Substantive applications include: Ongoing studies of cadmium toxicity in urine (Myrick), Rett syndrome (Myrick), Vermont mercury study (Myrick), serum dioxin study (Myrick); 2D DNA gels for identifying differentially expressed genes (Rogan et al.); radioactive fall-out from Chernobyl (Krekling); Aids Vaccine Program/FCRDC using image processing to improve: quantitative analysis of HIV-1 protein gels and Western blot assays (McGrath et al.) . GELLAB-II had been exported to: CDC/Atlanta (Myrick), Univ. Norway (Krekling), Univ. Zurich (Sonderegger). This year, CDC has been the primary Beta test site for GELLAB-II. Additional changes to help continued collaboration with and exporting of enhanced graphical-interface versions of GELLAB has been actively pursued and the primary activity this year.