Results obtained with a Technicon Flame Photometer Model IV Auto-Analyzer, which utilizes curve regeneration in conjunction with a mini-computer for the continuous-flow determination of serum electrolytes, is presented. The system, featuring optimal flow conditions, subjects sample peaks to a mathematical treatment to effectively remove exponential deformation. The evaluation, undertaken after 2 months of operation in the routine clinical laboratory, utilizes the Flame Photometer Model III as the "referee" procedure. The comparison includes a statistical analysis of quality control reference material, simultaneously determined patient data and an evaluation of repeated patient data. The system gave comparable results to those obtained for the Flame Photometer Model III and provides the additional benefits of increased sample throughput, decreased reagent comsumption and sample interaction and gives reductions in the clerical tasks associated with the retrieval of data from Auto-Analyzer systems.