Risk-adapted lymphoma treatment requires early and accurate assessment of prognosis. This investigation prospectively assessed the value of positron emission tomography with 2-[18F]fluoro-2-deoxy-D-glucose (FDG-PET) after two cycles of chemotherapy for prediction of progression-free survival (PFS) and overall survival (OS) in Hodgkin lymphoma (HL). Seventy-seven consecutive, newly diagnosed patients underwent FDG-PET at staging, after two and four cycles of chemotherapy, and after completion of chemotherapy. Median follow-up was 23 months. After two cycles of chemotherapy, 61 patients had negative FDG-PET scans and 16 patients had positive scans. Eleven of 16 FDG-PET-positive patients progressed and 2 died. Three of 61 FDG-PET-negative patients progressed; all were alive at latest follow-up. Survival analyses showed strong associations between early FDG-PET after two cycles and PFS (P < .001) and OS (P < .01). For prediction of PFS, interim FDG-PET was as accurate after two cycles as later during treatment and superior to computerized tomography (CT) at all times. In regression analyses, early interim FDG-PET was stronger than established prognostic factors. Other significant prognostic factors were stage and extranodal disease. Early interim FDG-PET is a strong and independent predictor of PFS in HL. A positive early interim FDG-PET is highly predictive of progression in patients with advanced-stage or extranodal disease.