Native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS)-PAGE are among the most frequently applied techniques in protein analysis. Here we describe a fast one-step method for fluorescent visualization of proteins. Following PAGE, gels are soaked in solution of potassium ferricyanide (100 mM) in 1 M NaOH, and are kept in the dark for 30 min. Gels are then transferred to water and scanned. The sensitivity of the method is comparable with standard Coomassie Brilliant Blue staining.