Introduction This chapter has as its focus the men who contribute their semen and who have traditionally been called semen donors. The term ‘donor’ is unsatisfactory, especially when, as frequently occurs, payment of money is involved. Other terms have been suggested: ‘vendor’, for a man who sells his semen (Annas 1980), and consignor, for a man who hands over his semen and his rights to it (Blank 1990). In this chapter the term ‘provider’ is used, as it describes both those who sell and those who gift their semen. While semen providers are being isolated for consideration in this chapter, they can not in fact ever be isolated. Their attitudes and behaviours impact on others and others' attitudes and behaviours impact on them. Semen providers evoke a variety of reactions. The thankfulness of some recipients is matched with the apprehension of others; different offspring report being thankful, and angry; doctors have concerns about the motivations of some of these men and committees set up to review the whole field reflect views varying from uncertainty, apprehension and disgust, through to the desire to value and applaud those who make this contribution. The fact that little has been known about men who become providers has almost certainly contributed to the variety of views held. Providers have in fact been hidden from public awareness and scrutiny and, as this chapter will show, it is only recently that there has been acknowledgement of their contribution.