A total of 16 healthy Friesian young bulls aged 15 months and averaged 291±15.6 kg live body weight was divided into two equal groups according to their live body weight. Bulls were housed in two different housing systems (tie-stall and loose bran) under the same environmental conditions to evaluate semen quality and some physiological responses during three seasons (winter, spring and summer). Air temperatures (AT, ^oC), relative humidity (RH %), temperature humidity index (THI), and body temperatures (BT) were recorded twice a day at 08:00 hr and 14:00 hr. Blood samples were collected twice a month to evaluate the hemoglobin content (Hb, mg/dl), hematocrit values (Ht%) and testosterone hormone concentration (ng/dl). Semen was collected from all bulls under the two housing systems twice a week using an artificial vagina to evaluate the semen characteristics and morphology traits. Results showed highly significant effect (P<0.05) of the environmental conditions on bull physiological responses. The animal housing could affect the semen quality; however, it did not affect all the seminal traits which were investigated in this study. The seasonal variation was more effective factor that changing the semen quality than housing system types. Bulls showed better results under loose housing system in all seasons. Summer season where the THI reached 91 had negative effects on semen traits. It could be concluded that animal housing systems and seasonal variations can affect the seminal quality and some physiological parameters of Friesian bulls.