This paper investigates the way in which the numbers, N, of the comets that have been observed from Earth, vary as a function of their absolute magnitude M. After attempting to remove all the effects of observational selection it is concluded that N ∝ (2.02 ± 0.18)M. The low value of the numerical factor in the expression given above suggests that the mass distribution of comets is such that the majority of this mass resides in the largest comets. This is similar to the mass distribution of the asteroids.