Abstract: : The main objective of the present investigation was to evaluate the importance of scrotal circumference variation on semen characteristics of bulls used for Artificial Insemination (AI) programme, in Bangladesh. For this purpose, a total of 3720 semen samples were collected from 71 bulls at three AI centres/stations (CCBSDF, Savar, Dhaka, RDCIF, Rajabarihat, Rajshahi and DAIC, Rajshahi) from 1995 to 2002; inclusive. These bulls were classified into 4 groups according to their scrotal circumference (SC) such as Group-I: <34 cm, Group-2: 34-36 cm, Group-III: 36-38 cm and Group-IV: >38 cm. The semen characteristics of the average values with standard deviation of volume, colour, density, mass activity, sperm concentration, sperm motility, total number of sperm cells/ejaculate, total number motile sperm cells /ejaculate, number of semen doses /ejaculate, post-freezing motility of sperm and % of abnormal spermatozoa were 7.14?2.1ml, 3.23?0.9(scale:1-4), 3.56(scale:1-5), 2.91?0.81(scale:1-5), 1314.5?12.6 million/ml, 63.95?4.61%, 9375.7?3431.5million, 6023?2299million, 312.0?115.3, 55.09% and 16.38?3.2 respectively. Scrotal circumference groups had significant effect (P<0.05) on semen characteristics except on post-freezing motility of sperm. The volume, total sperm cells/ejaculate, total number of motile sperm cells/ejaculate and number of semen doses per collection were gradually increasing with the sizes of SC groups of bulls. The largest volume (8.53?2.07ml) was found in >38 cm with smallest (5.15?1.70ml) in <34 cm of SC groups. The variations of SC on % of total sperm abnormalities were found to be significant. The highest average percentage of total sperm abnormalities was recorded (17.00%) in >38cm followed by <34 cm, 34-36 cm and 36-38 cm of SC groups (16.76%, 16.39% and 15.73%, respectively). Again, Analysis of variance indicated that breeds of bull had significant (P<0.05) effect on scrotal circumference. Significant (P<0.05) highest SC (38.0+0.7 cm) in 100% Friesian and lowest (33.9=1.2 cm) in 100% Local bulls. Result suggested that SC of >38 cm group of bulls were suitable for better performance of semen characteristics as well as 100% Friesian bulls ware sound for top scrotal circumference of AI bulls.