Natural immunity, lymphocytes functions and cytokines responses, are dependent of the intensity, and duration of the physical effort. The study investigated some aspects of innate immune defence correlated with a submaximal effort on bicycle performed by 10 trained teenagers. Blood and salivary samples were collected before and after submaximal effort. Leucocyte's phagocytosis was determined by phagocytic index of nitrobluetetrazolium dye (NBT test %). After the effort, was observed leucocytosis, monocytosis (10±1.88 %), and the decrease of eosinophiles and lymphocytes (22.4±5.31%). Leucocytes oxidative metabolism, estimated by NBT test, was increased from 3.8±1.39% to 6.1±3.24% after the effort. The salivary leucocyte's number (1035±564.9/microliter) and their phagocytic capacity (5.2 ±1.54 %) were increased. The augmented levels of oral epithelial cells desquamation (1330±654.9 cells/microliter) associated with reduced cells viability (87.7± 8%), can produce the deficiency of natural oral mucosa barrier. The results showed the activation of nonspecific defence from blood and saliva in submaximal effort.