Summary-Thirty azoospermic patients with normal testes and normal serum FSH levels had scrotal exploration with photographic record of the appearance of the epididymes and vasography; bilateral epididymovasostomies were done if possible, with vasovasostomies if there were coexisting vasal blocks. Follow-up studies showed no success when the epididymes were empty (Type 11, when the vasa were absent or malformed (Type 21, or when tubular dilatation was confined to the heads of the epididymes; all of the latter cases had coexisting sinusitis, bronchitis or bronchiectasis (Type 4 —Young's syndrome). Five patients with post-inflammatory disease had epididymes distended down to their tails (Type 31, and 3 also had vasal blocks. Three achieved sperm counts greater than 1 0 million per ml and impregnated their wives. Ten of 1 6 vasectomy reversals done by a similar side-to-side technique were successful.

A simple classification of obstructive azoosperrnia is described and it is concluded that in about 50% of cases the underlying cause of failure in sperm transport remains obscure.