Should I let my 4 year old come to chemo therapy with me?!

I agree it's not really the best place for such a young child, as your treatment can take hours and there wouldn't really be anything for your daughter to do.
But, I think your reasoning about normalizing the situation and letting her get a sense of what's going on is great. Maybe you could have another adult bring your daughter in for a "visit" - maybe for ten minutes or so. That way, she sees what's going on but isn't bored and you don't have to be responsible while you are getting treatment. :)

Not if you have anyone to provide childcare, no.

There will be nothing for her/him to do except sit there with you as you sit in your chair receiving your treatment, and all this sitting will go on for a couple of hours or more.

The sweetest of four year olds is might get bored and fractious in those circumstances. And even if s/he doesn't, s/he may be noisy and demanding of your attention.

Now, you don't need that - and nor do the other people receiving chemo alongside you. Unkind as it may sound, I would not have appreciated the presence of a young child while I was receiving chemo.

There's nothing for her/him to learn or to see. It wouldn't be traumatic or anything, just boring beyond belief.

If you can, make suitable childcare arrangements

I like the answers from "thinking...", "lo_mcg", and "Lynn from Fl".
This is not a good idea - having a 4 year old sit with you.
He or she will not be allowed to run around the office.
Over twenty years I supervised thousands of people undergoing chemotherapy,
and no one ever brought a four year old or any child in to sit with them.
I think the youngest family member I saw in the office during chemo was ~18.
Often this is done in large rooms with several people in recliner chairs
fairly close together.
You can ask your doctor what he or she thinks about it.
We don't know which regimen you will be receiving.
Some requires several hours in the chair

MD hematologist and medical oncologist - cancer and leukemia specialist physician for 20 years

I'm inclined to say no. The person who answered before me said "he might offer support" but that's rather selfish. I'm sure you're not concerned about what's good for YOU but rather what's good for HER. (You didn't mention the gender of your child but I'm going to pretend it's a daughter because it's just as arbitrary as pretending it's a son.)

That said, I can't really give you an answer. I don't think I would let her come with you every time, but maybe once or twice if she's curious about what mommy's going through. If she's not curious, and you're just saying "mommy has a doctor's appointment" or something and she's satisfied with that answer, 4 is pretty young and it might be best to leave her in the dark about the rest. If the chemo appointments aren't terribly depressing and she seems afraid then it might be good to take her with you once or twice to show her that it's "all right."

Mind that I don't have kids and I've never been to chemotherapy. My mother has cancer and will be starting chemotherapy soon, and as her *adult* offspring (26) I hate being kept in the dark about these things because she thinks she's trying to protect me when in reality she's just making me worry more. An older child, like maybe 10 or so, might also benefit more from knowing what's going on rather than being "protected," but I'm not so sure a 4 year old knows enough yet for her imagination to be worse than reality, and exposing her to it might feed that imagination rather than quell it.

Most infusion centers would not allow your daughter to be in the treatment area. She would need to stay in a play area so as not to disturb the other patients or get into any of the toxic things/needles etc. I would leave her at home. A chemo infusion center is not a good place for kids to hang out.

No way. There are very ill people there and while he/she may distract you, they may be upset. I hope you continue to feel well.

Yes and no. Yes, because he might offer support. But I wouldn't. It traumatic and I wouldn't want to see it even though I'm 13.

Peole who aren't feeling well may not be pleased to listen to a child there.