Advanced stage follicular lymphoma (FL) is incurable by conventional therapies. In the present pilot clinical trial, we explored the efficacy and immunogenicity of a novel in situ immunotherapeutic strategy. Fourteen patients with untreated or relapsed stage III/IV FL were included and received local radiotherapy to solitary lymphoma nodes and intranodal injections of low-dose rituximab (5 mg), immature autologous dendritic cells, and granulocyte-macrophage colony-stimulating factor at the same site. The treatment was repeated 3 times targeting different lymphoma nodes. Primary end points were clinical responses and induction of systemic immunity. Five out of 14 patients (36%) displayed objective clinical responses, including 1 patient with cutaneous FL who showed regression of skin lesions. Two of the patients had durable complete remissions. Notably, the magnitude of vaccination-induced systemic CD8 T-cell–mediated responses correlated closely with reduction in total tumor area (r = 0.71, P = .006), and immune responders showed prolonged time to next treatment. Clinical responders did not have a lower tumor burden than nonresponders pretreatment, suggesting that the T cells could eliminate large tumor masses once immune responses were induced. In conclusion, the combined use of 3 treatment modalities, and in situ administration in single lymphoma nodes, mediated systemic T-cell immunity accompanied by regression of disseminated FL. The trial was registered at www.clinicaltrials.gov as #NCT01926639.