We went this past May with my twin boys and my one son was probably a little shy of 40 inches but with his sandals it helped a little. I was a nervous wreck the whole time as he was on the line even with shoes on but never had any problems. My boys are small for their age...people loved watching them ride BTMRR with their hands up in the air! It was awesome. Fingers crossed they grow a little more before our next trip so they can experience Everest as they both really wanted to ride that as well this past time.