The objective of this study was to determine the frequency of phylloides tumor (PT) in adolescent girls and young women (less than and equal to 25 years of age) and to define the clinico-pathological features of PT in this unusual clinical setting. This descriptive study was carried out at the Aga Khan University Hospital (AKUH) pathology department. All consecutive cases of PT diagnosed during the last sixteen years in the section of histopathology from 1st January 1990 to 31st June 2005 were included. Selection of cases was restricted to patients up to 25 years of age. A total of 42 cases of PT in up to 25 years of age were diagnosed. This comprised 11% of the total PT cases (total n=363). The number of benign (BPT), borderline (BLPT) and malignant (MPT) was identical i.e. 14 (33.3%) each. Clinically all cases presented with a solid, mobile, palpable mass. The mean age was 19.1 years (95% CI, 16.7-21.6), 21.9 years (95% CI, 20.7-21.9) and 19.7 years (95% CI, 17.2-22.3) in BPT, BLPT and MPT respectively. In majority of cases the surgical procedure performed was lumpectomy (50% of BPT, 78% of BLPT and 64% of MPT). High grade PT (BLPT and MPT) is an uncommon mammary tumor in adolescent girls and young women but seems to be occurring with increased frequency in the study population. This observation may indicate the biological behavior of PT in a high risk population, though chances of referral bias are also present. In view of the rarity of the disease, larger population studies are suggested to confirm our findings.