Physical training is known to increase the antioxidant defence system and reduce exercise-induced oxidative stress. However, intense physical aerobic and anaerobic training and competition such as those imposed on professional rugby players, can induce an increase of oxidative stress which can be implicated with the arrival of overtraining. The aim of this study was to test the effect of training and competition load on oxidative stress, antioxidant status, haematological, and cell damage markers in high-level rugby players during a competitive season. Blood samples were collected four times in one year. Oxidative stress (Rmax), antioxidant (vitamin E, uric acid, TAC, and lag phase), haematological (neutrophils and monocytes) and biochemical (CK and myoglobin) parameters, as well as training and competition load, and competition results were measured. Intense periods of training and competition (T1 and T4) induced a significant higher maximum rate of conjugated dienes oxidation (+67.2% in T1 and +40.6% in T4) compared to those observed at the reference time (T3). Those periods also induced an increase in uric acid (+6.9% and 3.2%), and inflammatory markers such as monocytes (+13.3% and 10.7%). On the other hand, vitamin E (-8.7% in T1) and lag phase (-23.0% and -14.7%) were lower during these periods showing a possible training-induced antioxidant down-regulation. The less intense period of training (T2) was accompanied by lower neutrophils (-8.5%), CK (-53.7%), and myoglobin (-16.2%) values. The results suggest that oxidative stress and antioxidant measurement are significant in the biological follow-up of athletes.