Purpose A large number of new therapeutic agents have been studied for patients with relapsed/refractory follicular lymphoma (FL). Among new therapies, idelalisib, a novel PI3K inhibitor, shows promising results in the management of this disease. Case report We describe the case of a 39-year-old patient with a diagnosis of grade 3a FL and a Follicular Lymphoma International Prognostic Index score of 2, who underwent several lines of therapy (including autologous stem cell transplant) with transient responses or no response at all. The patient was subsequently treated with 5 courses of idelalisib monotherapy, achieving a partial response. No relevant toxicities occurred. The patient underwent allogeneic stem cell transplant (allo-SCT) from an unrelated donor and obtained a complete response, which was confirmed after 3, 6, 9, and 12 months, and is still ongoing. Conclusions As previously reported, the achievement of a good response is predictive for a better outcome after allo-SCT: idelalisib represents an effective treatment option for patients with relapsed/refractory FL, which can also be adopted as a bridge to allo-SCT.