Title of the paper: <b>Modifying influence of 11-months training on results of ‘timidity’ test of young half bred stallions</b><br> 78 three-year-old stallions of warm blooded Polish breeds and foreign breeds, kept at the training Centres, were investigated during the period 1998–2001. Stallions had to qualify for a 100-days training, after they passed it, they had to perform an 8-month training program in a central station. To estimate the degree of nervous balance of horses "timidity" a (optical) test was used. Stallions were putt to the tests three times: after qualifying to Training Centre, after completion 100-days training, after completion 8-month training. Stereotypes of stallions maintenance were graded from points 1 to 10. Stallions were divided onto three groups: hyper excitable (1.0–4.0 p), medium excitable (4.1–6.0 p), calm (6.1–10.0 p). Applied "timidity" test showed considerable usefulness to fast and evident opinion of equilibration of nervous system. Rising score in "timidity" test after 100-days as well as 8-months shows the training process had a modifying influence on stallions’ nervous excitability in this period. Largest nervous equilibration was observed at the offspring's of Holstein breed sires’, most excitable after the whole training period were offspring's of noble half bred sires. The highest score of nervous balance after 8-month training was observed at offspring of English thoroughbred sires.