The three experiments were carried out to assess the effect of pig behaviour on the daily emission of NH3. Under normal housing conditions the correlations (r) between NH3 emission and the duration of feeding or drinking, moving and lying were +0.78, +0.73 and -0.77, respectively. The coefficient of determination (r2) of the model was 0.662. Under ionization conditions, similar r were observed (+0.67, +0.54 and -0.67, respectively, the r2=0.596). Under increased air flow rate, the values varied widely.The correlations were +0.38, +0.38 and +0.39, respectively (r2=0.350). Daily values of NH3 per one head were 8.16, 9.92 and 5.81 g under normal conditions, under increased air flow rate and under ionization conditions, respectively.