The mayority of studies on neutrophil function in malnutrition has been assesed using peripheral blood cells (PB) However, in vivo, the extravascular tissues are the main play where PMN interact with offending microorganisms. Observations with PB PMN may be no representative of the functional capacity (FC) of EV PMN. The objective of the present study was to evaluate the FC of PMN in a experimental model of malnutrition. Eleven adul Wistar rats were fed a restricted diet to achieve a 20% wt. loss; 10 healthy rats formed the control group. Two sterily cilindrical, polyvinil sponges were implanted subcutaneously in the dorsum of all animals. After 24 hrs, sponges were aseptically removed, weighed and the PMN quantitated (purity and viabily> 90%), as the in vivo PMN migration response. Simultaneously, PB was obteined from all animals, and PMN isolated by dextran gradient sedimentation. The FC of PB and EV PMN was assayed by the quantitative nitroblue tetrazolium (NBT) dye reduction test, using Saccharomyces cerevisiae particles as phagocytic stimuli. The in vivo migration of PMN in malnourished animals was significantly lower compared to healthy animals (1.5± 0.09 × 10 vs 7.15 ± 2.5 × 10, PMN/sponge) (p<0.01). There were no differences in the phagocytic capacity of PB and EV PMN in healthy animals (0.360 ± 0.13 vs 0.370 ± 0.15). Similary, the phagocytic response of PB PMN from malnourished rats was comparable to control group (0.320 ± 0.16). However, the EV PMN from malnourished animals exhibit a significant reduction in the NBT response(0.135 ± 0.06, p<0.05). These results suggest that in malnutrition a significant decrease in the in vivo migration and phagocytic capacity of EV PMN can be observed. These data adds an aditional explanation for the greater suceptibility host to bacterial infections.