Purpose. The aim of this study was to evaluate whether intratesticular arterial resistance and testicular volume differed between infertile men with subclinical varicoceles and infertile men without varicoceles. Materials and Methods. Fifty-eight infertile men were examined by gray-scale and color Doppler sonography for presence of varicocele, testicular volume, and arterial resistance. For men in the study group, mean testicular volume and resistance index (Rl) in testes with varicoceles were compared with those in the contralateral testis by the paired t-test; statistical analyses between the study and control groups were performed by independent t-tests. Results. Twenty-seven men had left-sided varicoceles (96% of which were subclinical), and 31 infertile men without varicoceles served as controls. Mean volumes of the right and left testes of study subjects were 14.8 ml and 14.6 ml, respectively, and in controls were 14.2 ml and 13.6 ml, respectively. Mean Rl values for the right and left testes of study subjects were 0.61 and 0.58, respectively, and in controls were 0.61 and 0.58, respectively. There were no statistically significant differences in volume or Rl, either between the right and left testes within patient groups or between the control and study groups' combined mean values. While the mean intertesticular volume differences for the study and control groups were 2.2 ml and 3.4 ml, respectively, the mean intertesticular Rl differences were 0.04 and 0.07, respectively. These values also did not differ significantly between the 2 groups. Conclusions. Subclinical varicocele is not associated with ipsilateral testicular atrophy, and does not affect the intratesticular arterial Rl. (C) 2004 Wiley Periodicals, Inc.