Skin rash is an adverse event which might be associated with longer survival in patients treated with epidermal growth factor receptor tyrosine kinase inhibitors. The aim of this nonrandomised phase II clinical trial is to prospectively evaluate the relationship between skin rash and overall survival (OS) in advanced/metastatic pancreatic cancer treated with erlotinib plus gemcitabine. Patients were given gemcitabine (1000 mg/m2/week, 3 weeks every 4 weeks) plus erlotinib (100 mg/day orally continuously) until disease progression/unacceptable toxicity. The primary end point was OS. A total of 153 eligible patients were enrolled (grade ≥ 2 rash, 25%; grade < 2 rash, 75%). OS was longer in patients with grade ≥2 rash versus grade <2 (11 versus 5 months; P < 0.001). Progression-free survival was longer in patients with grade ≥2 rash versus grade <2 (6 versus 3 months; P < 0.001) and shorter in those without rash versus grade 1 (2 versus 4 months; P = 0.005) or grade ≥2 (2 versus 6 months; P < 0.001). Patients with grade ≥2 rash showed higher rates of overall response (21% versus 7%; P < 0.05) and disease control (84% versus 43%; P < 0.05) versus grade <2. This study prospectively confirms the relationship between rash and longer OS in unresectable locally advanced/metastatic pancreatic cancer treated with erlotinib plus gemcitabine.