Polymorphisms in detoxification enzymes of the glutathione S-transferase (GST) family have been associated with risk and prognosis of several cancer types. We studied deletions of GSTM1 and GSTT1, and the GSTP1 Ile(105)Val polymorphism in 89 patients with follicular lymphoma (FL). Patients with a GSTM1 or GSTT1 deletion had a significantly worse event-free survival, when compared with patients with undeleted genotype (p = 0.03 and p = 0.03, respectively). Outcome was even worse in patients with a double negative genotype, in comparison with patients with only one GST deletion or normal genotype (p = 0.01). In the multivariate analysis, the GSTM1/GSTT1 genotype tended to have a prognostic significance independent from the Follicular Lymphoma International Prognostic Index (FLIPI) score. In particular, GSTM1/T1 deletions identified patients with negative prognosis in the low (<3) FLIPI score group (p = 0.01). Larger prospective studies including homogeneously treated patients will be needed to confirm these results.