Objective: To study the prevalence and immunohistochemical profile of the subtypes of anaplastic large cell lymphomas (ALCLs) at a major referral center of Pakistan. Methods: Epidemiological data for all mature T-cell non-Hodgkin’s lymphoma (NHL) diagnosed between 1st January 2005 and 30th June 2010 at the Aga Khan University Department of Histopathology were reviewed and analyzed with SPSS v17.0. Results: A total of 178 specimens were diagnosed as mature T- and NK- cell NHL during the period. Of these 100 (56.2%) were diagnosedas systemic ALCL. These tumors were of either T- or null-cell type with consistent (100%) expression of CD30(Ki-1). Forty three (43%) cases were further classified as ALK positive, fifty (50%) as ALK negative and seven(7%) were not tested for ALK expression. The mean age of the ALK positive group was 26.7 years as comparedto the ALK negative of 35.6 years. The gender ratio of ALK positive cases was 2.3:1 (M:F) as compared to the2.5:1 ratio seen in the ALK negative cases. There were no significant differences in the nodal and extra-nodal involvement patterns between ALK+ and ALK- groups but epithelial membrane antigen was positive more often in the ALK positive group. Conclusion: Compared to other published studies, this proportion of ALCL within the mature T- and NK- cell lymphoma category was found to be alarmingly high and calls for attention. Further studies should be conducted in our region, which in turn would enable clinicians to successfully battle against this neoplastic disease.