Three non-invasive methods for the detection of a varicocele were evaluated in 63 men presenting with infertility. Physical examination, varicoscreen contact thermography and colour Doppler ultrasound were compared with spermatic venography as reference strategy. Physical examination had a sensitivity of 71%. Whether the non-palpable varicoceles are all subclinical is questionable since the specificity of physical examination was 69%. Varicoscreen proved be quick, easy and cheap but of no clinical value (sensitivity 97%, specificity 9%). Colour Doppler ultrasound using strict criteria was a good diagnostic tool (sensitivity 97%, specificity 94%). No imaging difference was seen with colour Doppler ultrasound among clinical and subclinical varicoceles. Since the debate on treating all degrees of varicocoeles is ongoing, we suggest that Doppler sonography should be a routine examination in infertile men.