Human milk is bodily fluid which has proven to contain a variety of immune components such as antibodies, growth factors, cytokines, antimicrobial compounds and specific immune cells(1). Breast feeding has been shown to enhance the development of the immune system of the newborn as well as provide protection against enteric and respiratory infections (2). Excess milk can be donated by mothers to milk banks which are then subjected to pasteurisation to extend storage life as well as to prevent transmission of infections(3). However, little is known about the impact of this heat treatment on the immune and nutritional components. The concentrations of TGF-beta (Transforming Growth Factor), IL1 (interleukin1), IL10 (interleukin 10), RANTES (Regulated on activation, normal T cell expressed and secreted/ CCL5), IL8 (interleukin 8), IL6 (interleukin6) and sIL6R were measured by ELISA in both fresh and banked milk. Significant differences were noted in the concentrations of RANTES: fresh breast milk (1548 +/- 373 pg/ml, n =31, p = 0.001), banked samples (875 +/- 1181 pg/ml, n = 4, p = 0.001). Similar differences were observed for TGF-beta between fresh milk samples (8047 +/- 4350 pg/ml, n = 31, p = 0.018) and banked samples (1989+/-321 pg/ml, n = 4, p = 0.018). No IL1 was detected in any of the banked samples, with an average of 1 pg/ml in the fresh samples. No significant difference between levels of IL10 in fresh and banked samples was observed. However, IL8 (p= 0.004) as well as IL6 (p= 0.008) levels were significantly reduced in banked samples when compared to the fresh samples. Soluble IL6 receptor level was greatly reduced to a level of no detection in banked milk (24033 +/- 14125 pg/ml, n=20, p=0.04).These results suggest that pasteurisation may reduce levels of certain cytokines and chemokines in human breast milk and may therefore impair the immunological benefits of breast feeding.