Old commune of Ille-et-Vilaine, Saint-Melaine (1 214 inhabitants in 1999) formed today part of the commune of Châteaubourg. Broons-on-Unpleasant fusion-association between , Saint-Melaine and Châteaubourg took place in 1973.

The parish is devoted to Saint Melaine, bishop of Rennes.

Saint-Melaine was set up in commune with the French revolution, with the detriment of the current Saint-Jean-on-Unpleasant commune of .