The answer to that question is yes and no. The plant is a member of the nightshade family of plants that includes eggplant, peppers and the deadly nightshade. It is because of that relationship with the nightshade the green part of the plant can be toxic in varying degrees.
There have been accounts of cattle getting into tomato fields and eating large quantities of the green plant. The result was that some of the cattle died. The plant contains an alkaloid which in small amounts will not produce any harmful effects. It is the amount ingested that will produce any harmful toxic levels.
The unripened, green tomato fruit that has been fried, pickled or otherwise processed in some way has no harmful effects what so ever.
After 200+ years of commercial cultivation there are still people that believe the tomato fruit is poisonous.
