Visiting St Peters Basilica in May
 

Can anyone tell me what the queues are like for security in the late afternoon?
I think I've read everything I can find on visiting the Vatican but still can't make a decision. I will be booking a ticket to the Vatican museum so we can see the Sistine Chapel, and I know about the left door and the right door to exit BUT I'm concerned we will be not allowed to use the right door so we'll have to walk all the way around and join the queue outside the basilica. I also know I could book onto a tour of the museum and St. Peter's and then it wouldn't be a problem BUT I'm not really keen on tours. So I thought we would go to St. Peter's early in the morning or late in the afternoon BUT I'm not good at getting up early.

Do you know google? Feed "st peters queue images" into google search and you see what queues look like in the afternoon. You can enter St. Peters with a short security queue well before 9am. I have entered the Basilica around 5pm one time. While it seems to have gotten shorter than mid day, it was still much longer than at 8am. Inside was a very very crowded even at that later afternoon.

Early bird gets the worm :-)

This is one time when it pays to get up early. I've seen lines start forming at 7.30am. There is nothing like being one of the first inside the Basilica.
If you're planning going some time this year, remember it's a Holy Year so lines are going to be even longer, with people entering the Holy Door even being given timeslots to avoid congestion.

Not so long ago, the security queues were very short in the late afternoon, after 5 PM. However, this past June, I was there at around 5:30 PM, and the queue went all the way around the square. I don't know if it's always like that. Since they close at 7 PM, getting there any later than that wouldn't give you much time to see the Basilica. I would suggest going very early, as others have suggested.

We were in Rome last October. I visited the Vatican on one day when in Rome and purchased our tickets in advance. The queue for St. Peter's was long and the weather was very warm. I did some research when I returned to,the hotel that evening and found that there were ticket vendors that you could pay and they would get you to the front of the queue. Once you got into St. Peter's you were on your own - no tour. I paid 15€ for one person. It was so worth the money! When we walked along the area there are many people that ask you if you want a tour. I asked several people about finding the right person to skip the queue and was successful. From the time I found the vendor I probably waited about 45 minutes before I was inside St. Peter's.

Maureen you paid 15 euro just to jump to the front of the security line?
St. Peter's Basilica is free.
If the OP manages their time they don't have to wait very long - avoid times from 9am to 3pm. The line is just to scan belongings and walk through a metal detector so it moves fairly quickly.