We study the work fluctuations of a particle subjected to a deterministic drag force plus a random forcing whose statistics is of the Lévy type. In the stationary regime, the probability density of the work is found to have "fat" power-law tails which assign a relatively high probability to large fluctuations compared with the case where the random forcing is Gaussian. These tails lead to a strong violation of existing fluctuation theorems, as the ratio of the probabilities of positive and negative work fluctuations of equal magnitude behaves in a non-monotonic way. Possible experiments that could probe these features are proposed. The study of fluctuations in systems driven in nonequilibrium steady states has concentrated lately on a special symmetry property referred to as the fluctuation theorem or fluctuation relation. The first studies of this symmetry focused on the entropy production of nonequilibrium systems [1,2], but it was soon realized that the same symmetry holds for other quantities of interest, such as the work W τ performed on a nonequilibrium system during a time τ [3]. In the context of this quantity, we define a fluctuation relation [4] as follows. Assuming that W τ is extensive in τ , we say that the probability density P (W τ ) of W τ satisfies a fluctuation relation or, to be more precise, a conventional fluctuation relation ifwhere c is a constant which depends neither on τ nor w.We also say that P (W τ ) satisfies a conventional fluctuation relation if the above equality holds, when properly scaled (see below), in the limit τ → ∞. In that case, we speak of a stationary conventional fluctuation relation.One important problem about fluctuation relations, which is as yet unresolved, is to determine the class of nonequilibrium systems or, more precisely, the class of nonequilibrium observables [5] whose fluctuations satisfy a conventional fluctuation relation. Our understanding of this issue at this point is that this relation holds for two general classes of systems: (i) finite, deterministic systems having a sufficiently chaotic dynamics [2,6], and (ii) finite, stochastic systems whose evolution is a Markov process [7]. There are subtle points to be taken into account, however. In some cases, boundary conditions or special forms of large deviations may restrict the range of validity of conventional fluctuation relations, and in these cases, corrections or extensions of the conventional fluctuation relation have been proposed [8,9].Our goal in this paper is to expand this picture of fluctuation relations by studying a model of a nonequilibrium * Electronic address: ht@maths.qmul.ac.uk system whose work fluctuations neither obey the conventional fluctuation relation nor the extended fluctuation relation of van Zon and Cohen [8]. Based on this model, we propose a novel type of fluctuation relation, and compare it, from the general point of view of large deviation theory, with the conventional fluctuation relation defined in (1). In the end, we also discuss two experiments for which "anomalous"...