There are 11 words that start with 'merca'.
| mercapto | mercaptan |
| mercantile | mercaptans |
| mercantilism | mercantilist |
| mercantilisms | mercantilists |
| mercantilistic | mercaptopurine |
| mercaptopurines | |
Note: These 11 words that start with 'merca' are found from the USA & Canada version of the tournament Scrabble word list.