We let the memory foam unfold in a spare room and air out for almost a week. I didn't notice any obvious odor upon removing it from the box, but my spouse insisted we let it "air out". We need a new mattress but wanted to put off the purchase for a bit. This particular memory foam and mattress topper looked great on-line, the item description was appealing, and the collection got many great reviews. The fit of the foam and mattress topper are perfect. The foam doesn't shift (move) around on top of the mattress and we love the deep pocketed mattress topper. The very best thing is how comfortable our bed is now. We both l-o-v-e this purchase and are likely going to buy one for the bed in the guest bedroom - even though that bed is new, this mattress topper is so comfortable and cozy, I want guests to have a great night's sleep too. We are very happy with this purchase.