Ninety-six Awassi ram lambs, aged 2-3 months, raised and managed under a semi intensive system were used to measure development of testicular length, width, circumference and volume, and their association with development of body growth. The effects of parental size, age and body weight of lambs, production line (dairy or meat), type of birth and weight at birth and weaning on development of the four testicular parameters from weaning at 2-17 months of age were investigated. No significant differences were observed between measurements of the left and right testis. The highest increase in testicular parameters occurred between 7 and 10 months of age at 34.6kg live body weight. Only parental size, age and body weight affected testicular growth (P<0.05). Measurements of testes were correlated (P<0.01) with each other (r=0.68-0.97). They increased progressively and were correlated with body weight more than with age.