 Of the population in the municipality, 434 or about 32.9% were born in Massongex and lived there in 2000.There were 377 or 28.6% who were born in the same canton, while 291 or 22.1% were born somewhere else in Switzerland, and 186 or 14.1% were born outside of Switzerland., children and teenagers (0–19 years old) make up 27.7% of the population, while adults (20–64 years old) make up 61% and seniors (over 64 years old) make up 11.2%.