The objective of the current study was to assess the prognostic factors in patients with extranodal natural killer (NK)/T cell lymphoma, nasal type (ENKL). We retrospectively analyzed 35 patients who were diagnosed with ENKL between 1998 and 2011. The median patient age was 63 years, and the male/female ratio was 22:13; twenty patients had localized ENKL, and 26 had a good Eastern Cooperative Oncology Group performance status (score 0 or 1). B symptoms were present in 17 patients. Twenty-five patients presented with nasal or paranasal lesions, or both. With a median follow-up duration among patients still alive at their last follow-up of 47 months (range 8-93 months), the 3-year overall survival (OS) rate was 44.5 %. Multivariate analysis revealed that advanced disease stage (P = 0.002), the presence of extranasal disease (P = 0.013), and serum ferritin levels greater than 300 ng/ml (P < 0.001) were significant and independent (negative) prognostic factors. High serum ferritin levels were associated with the presence of B symptoms, elevated lactate dehydrogenase levels, and high soluble interleukin-2 receptor levels, but not with clinical stage. Patients with high ferritin levels had a remarkably low remission rate (23 %) and a short OS time (median: 4 months). Serum ferritin level at the time of diagnosis of ENKL was a useful prognostic factor.