Gemcitabine is effective in the treatment of pancreatic cancer and is a potent radiosensitizer. This study assessed safety and efficacy of full-dose gemcitabine administered before and during concurrent three-dimensional conformal radiation (3D-CRT) in patients with nonmetastatic pancreatic cancer. During cycles 1 and 3, patients received gemcitabine at 1,000 mg/m(2) on days 1 and 8 of each 21-day cycle. Cycle 2 included the same dose of gemcitabine on days 1, 8, and 15 of a 28-day cycle with concurrent 3D-CRT at 36 Gy, administered in 15 fractions of 2.4 Gy, over 3 weeks. Resectable patients underwent surgery 4 to 6 weeks after treatment. The primary objective was evaluation of toxicity. Tumor response, CA 19-9, and 1-year survival were also assessed. Forty-one patients enrolled at six institutions between April 2002 and October 2003. Among the 39 treated patients, the most common toxicities were grade 3 neutropenia (12.8%), grade 3 nausea (10.3%), and grade 3 vomiting (10.3%). The response rate was 5.1% and disease control rate was 84.6%. Mean post-treatment CA 19-9 levels (228 +/- 347 U/mL) were significantly (P = .006) reduced compared with pretreatment levels (1,241 +/- 2,124 U/mL). Thirteen (81%) of 16 patients initially judged resectable, three (33%) of nine borderline-resectable patients, and one (7%) of 14 unresectable patients underwent resection after therapy. One-year survival rates were 73% for all patients, 94% for resectable patients, 76% for borderline-resectable patients, and 47% for unresectable patients. Full-dose gemcitabine with concurrent radiotherapy was well tolerated and active. Evaluation of this regimen in a larger, randomized trial for patients with resectable or borderline-resectable disease may be warranted.