Slightly visible blue vein on my leg. is this a varicose vein?

Probably not.: Varicose veins are large, bulging grape-like veins while blue veins which are not large, bulging or grape-like are usually reticular or feeding veins. These blue veins are essentially the veins between the small spider veins and the larger varicose veins.You should see a vein specialist for an evaluation.

Maybe: A vein like this can be a varicose vein or it may just be a prominent vein that is close to the skin.

Need Exam to Answer: You need a physical exam by a vein specialist, known as a vascular surgeon, to determine if your leg veins are normal are diseased. Although certain characteristics of the veins, such as bulging, enlargement, serpentine shape, pain / tenderness, etc can help one to determine whether the vein is varicose, it is best to have an expert trained eye look at it and give you a diagnosis. Sent a photo!

Yes and no: it could just be a visible vein not necessarily varicose vein