flowergift, I am not as familiar with Jasmine as I am with other plants, but I'm thinking that you are keeping it in the house. Is it getting enough sunlight? Also check the leaves (top and bottoms) for a tiny insect, usually white in color.
Often times when plants are brought into a different environment, they suffer from stress that leaves them weaken and they can be prone to insects. Tiny white (whitefly) or red (spidermites) insects are the usual culprit. They will cause the leaves to drop. Check for those. You should be able to see them clining to the vine or the leaves that are left.
Before you water it again, stick your finger to your first knuckle into the soil and see if it is wet or moist. If so do not water it. To much water can also cause it to drop leaves. Allow the soil to dry to the touch before you water it again. Also, does the pot have a hole in the bottom? This is extremely important for drainage. The plant will not like sitting is a pot that is soaked with water. The pot must be able to drain itself. Keep a saucer under it to catch any seeping water. Somehow I seriously think water is your problem.
Also check the amount of sunlight your plant gets. It should be kept at a bright window. Here is a site that might help you with its care.
http://www.theflowerexpert.com/content/giftflowers/
flowersandfragrances/jasmine
Good luck. Let us know how you fare with it.
