Recommended translations:

• Plato's Dialogue on Friendship: An Interpretation of the Lysis, with a New Translation, trans. David Bolotin (Cornell, 1979).
• "Lysis," trans. S. Lombardo in Plato: Complete Works, ed. J. M. Cooper (Hackett, 1997).

Excerpt:

Ah well, I said, Hippothales, what an altogether noble and gallant love you have discovered there! Now please go on and give me a performance like those that you give your friends here, so that I may know whether you understand what a lover ought to say of his favorite to his face or to others.

Do you attach any weight, Socrates, he asked, to anything you have heard this fellow say?

Tell me, I said; do you deny being in love with the person he mentions?

Not I, he replied; but I do deny that I make poems and compositions on my favorite.

Online:
Amazon (Recommended Translation: Bolotin)
Amazon (Recommended Translation: Lombardo)
Project Perseus (English, Free Access)
Project Perseus (Greek, Free Access)
Project Gutenberg (Free Access)