Pour chicken broth into a large pot, and bring to a boil. Add orzo pasta, and simmer for 10 minutes, until tender.
In a medium glass or metal bowl, whip egg whites to medium stiff peaks. Stir in egg yolks and lemon juice. When the pasta has finished cooking, Gradually ladle about 1 cup of the soup into the egg mixture while stirring gently. This will heat up the eggs so they will not be shocked by the boiling liquid. Pour the egg mixture into the soup pot, and stir until well blended. Season with salt and pepper, and serve immediately.