In response to your note to me:
I am glad its mainly you he is biting and pinching (sorry for you though). It makes it a lot easier to deal with. He is kind of in the "puppy dog" stage of trying to get attention. You need to look at when he is doing this cause it changes your response. If he is mad and he is lashing out at you - then its timeouts - never anything physical - and explaining why this is wrong afterward. If he is not mad then, then its probably more of a playful, getting attention type of thing.
You need to get his attention, warn him, and then if he repeats - a timeout. Realize, that it may take a couple of weeks of being very consistent for this to work.
You also might explore giving him other means to use instead of biting. If he is angry - a way to express this and then physically burn it off. If he is looking for attention, then a more effective and easier way of getting it. Don't just tell him these ways - role play it several times and certainly after each incident.
Also please realize that with ADHD, he doesn't have the filters to stop these behaviors at this age. That really makes how you discipline so important. Its gotta be with lots of love. Its really possible that he isn't really even realizing he is doing this till its been done. That is why it is so important to try and teach him other ways of communicating.
Good Luck!
It depends a lot on the age of your child. Of course, if the child is on meds on not, is also important to know. Also, who is your child biting? You? Kids at school? Playmates? Everyone? Is it worse at any time of the day?