A very sensitive survey of the CO(2-1) emission of the entire disk of the Local Group galaxy M 33 is virtually complete. Hundreds of clouds down to a mass of 10000M&sun; are detected and we show that the cloud mass function (assuming a constant ratio between CO emission and H2 mass) steepens away from the center of M 33. Through comparison with dust emission and cloud Virial masses, we estimate a N(H2)/I CO factor roughly twice Galactic.