Penicillin wasn't discover in the twentieth century, was it? It was discovered in 1912.
[AD]
Relevant question
[AD]
Answer`s (7):
1. nik
1912 *is* the 20th century.

I'd say Aspirin though. Actually this one's been adapted by Bayer in 1897 which makes it very late 19th century, but I'd still say that this is THE health advance. What in the world would we do without aspirin?
2. brosimbe
Thats easy, ADHD drugs, I have 11 grand children and with out these I would be CRAZY.
3. taxed till i die,and then some.
Clean drinking water.
4. Mr. Know It All
Polio vaccination or wiping out small pox.
5. dave dodgy knee
GP's sicknote, lol
6. suziejoy
1912 was the 20th centuary!!!!!!!!!!!!!
7. TOM
smallpox