It is not necessary to devein shrimp, but generally, any shrimp big enough to have a visible vein should be deveined. Inside that vein is digested material and sand that needs to be purged from the shrimp's body. Leaving the vein in can also produce a gritty texture in the shrimp.

Fresh or thawed shrimp that has not been cooked is very perishable. Shrimp should be used within two days of purchase to ensure optimal taste and texture. Store fresh shrimp that will not be cooked immediately in the coolest area of the refrigerator, preferably on ice and covered with waxed paper. The waxed paper allows air to circulate around the shrimp.

If the heads are attached, twist them off to remove. Discard or save for stock. If you are right-handed, hold the shrimp in your left hand with outside curve up and tail away from you. Using clean kitchen scissors carefully cut through the shell along the top of shrimp to just before the last section of shell, below the tail. Peel back shell and remove shell keeping the tail intact. Discard shells or keep them for stock. Hold peeled shrimp under running water. With paring knife, remove black vein along cut side of shrimp.

If you want to butterfly the shrimp: Complete the steps above, leaving the tails on, then slit the back of shrimp from tail to head, about 2/3 through.

Also see our R4L Guide to Preparing Seafood