Some great pork tenderloin marinades include lemon-bourbon-rosemary marinade, Asian sesame marinade and mustard-and-wine marinade. You can also make a good, simple marinade from fresh herbs and spices.
To make an herb marinade, add 3/4 cup of fresh lemon juice and 1/2 cup of olive oil to a bowl. Mix in the zest from 1 lemon, 2 tablespoons of minced garlic, 1 1/2 tablespoons of minced fresh rosemary leaves, 1 tablespoon of minced fresh thyme leaves, 2 teaspoons of salt and 2 teaspoons of Dijon mustard. Combine all the ingredients and pour into a resealable bag. Add the pork tenderloins, and refrigerate for three hours before cooking.
For an oriental flair, make an Asian-based marinade mixing together 3 tablespoons of soy sauce and 1/4 cup of ginger dressing. Place the mixture in a bag with the tenderloin, and chill for 10 minutes before cooking. Marinate pork tenderloin in a mixture of 1/2 cup of bourbon, 1/4 cup of fresh lemon juice, 2 minced garlic cloves, 2 tablespoons of olive oil and 1 teaspoons of minced fresh rosemary. Cook the pork on skewers with fresh peaches to make kabobs. Another great marinade uses only five ingredients: 1 1/4 cups dry white wine, 1 cup of chicken broth, 2 tablespoons of mustard, 1 teaspoon of minced garlic and 1 tablespoon of fresh thyme. Pour the ingredients and the pork tenderloin in a bag to marinate overnight.