The Golgi-Cox method has been one of the most effective techniques for studying the morphology of neuronal dendrites and dendritic spines. However, the reliability and time-consuming process of Golgi-Cox staining have been major obstacles to the widespread application of this technique. To overcome these shortcomings and to promote this invaluable technique, we developed the FD Rapid GolgiStain™ Kit based on the principle of the methods described by Ramón-Moliner in 1970 and Glaser and Van der Loos in 1981. The kit significantly improves and simplifies the Golgi-Cox technique. This kit is reliable for visualizing morphological details of neurons, allowing for analysis of various parameters of dendritic morphology-such as dendritic length and branching pattern and dendritic spine number, shape, and size-in both animal and postmortem human brains. A 40-min instructional video for tissue freezing, cryosectioning, and staining is provided. © 2019 by John Wiley & Sons, Inc.