A new mixed-valent (Nb-V/Nb-IV) Zintl phase, Cs9Nb2As6, has been prepared and characterized, recently (Gascoin, F; Sevov, S. C. Inorg. Chem. 2002, 41, 5920). Niobium is present in the form of isolated, edge-sharing tetrahedral, Nb2As69- dimers. The reported magnetic susceptibility features a broad maximum at similar to36 K which has been interpreted as the onset of long-range antiferromagnetic order. Such a high transition temperature is difficult to understand as the compound is insulating and the interdimer Nb-Nb distance is 7.2 Angstrom. It is shown here that the observed magnetic properties follow straightforwardly from a statistical occupation of the equivalent intradimer Nb sites by equal concentrations of Nb-IV(4d(1), S = 1/2) and Nb-V(4d(0)), From this analysis the broad maximum arises from intradimer antiferromagnetic exchange with an exchange constant, J/k = -40 K, and there is no long-range magnetic order except, possibly, below 5 K.