How many mitzvos nowadays can be done in practice? The Chofetz Chayim compiled a book called Sefer HaMitzvos Hakozer that lists out of the 613 mitzvos how many can be done nowadays. This is because a lot of mitzvos involve korbonous. sacrifices, and the holy Beis Hamikdosh that has been destroyed. He lists 77 positive commandments and 194 negative commandments.