Aims: In a previous phase III study the FUFOX regimen has shown superior response rates to bolus 5-FU/FA (Mayo Clinic protocol) in patients with MCRC (Grothey, ASCO 2002). The combination of capecitabine (CAP) and oxaliplatin (OX) has demonstrated good efficacy and safety results in recent phase II studies. In August 2002 we initiated a phase III trial to compare FUFOX and CAPOX as first line therapy in patients with MCRC. Here, we present the results of the planned interim safety and efficacy analysis. Patients and methods: From August 2002 to August 2004 476 patients (m: f=299: 177; median age 65 (range 32–86)) have been randomized to receive either FUFOX (234 pts. arm A: 5-fluorouracil 2000mg/m² 24h infusion, folinic acid 500mg/m², oxaliplatin 50mg/m² d1,8,15,22; q5 wks) or CAPOX (242 pts arm B: capecitabine 1000mg/m² bid d1–14, oxaliplatin 70mg/m² d1 and 8; q3 wks). All patients had measurable metastatic disease, ECOG performance status 0–2, normal renal and hepatic function. Results: To date 2123 treatment cycles (841 FUFOX, 1282 CAPOX) are evaluable for toxicity (median number of cycles per patient: arm A: 4, range 1–10; arm B: 6, range 1–19, table 1). Based on 233 events currently observed, median time to tumor progression (primary study endpoint) was 34 weeks in the FUFOX arm and 31 weeks in the CAPOX arm (p=NS). Secondary efficay parameters are detailed in table 2. Conclusions: These data show for the first time that both FUFOX and CAPOX have comparable toxicity profiles and response rates in first line treatment of ACRC. Updated toxicity and efficacy results will be reported at the meeting.