See Propecia-induced spermatogenic failure: A report of two cases. by Liu KE, Binsaleh S, Lo KC, Jarvi K.
The conclusion of the article states:
Two cases of infertile patients with azoospermia or severe oligospermia who showed significant improvements in sperm concentrations 6 months after the discontinuation of finasteride. In one case, improvement in semen parameters prevented the need for testicular biopsy and corrected the azoospermia. Stopping finasteride in the infertility population may improve semen parameters, and may allow for less invasive fertility treatments.
We have already heard about similar, more frequent side effects with Avodart (dutasteride). While I am not completely surprised, I suspect the frequency is very low. I’ve written about sperm count and Propecia in the past: