To be honest, I sat in the bathroom with him until he was comfortable with the process. Stinky, but effective. It taught him how to relax and I just slowly worked myself out of the room and he is fine now.

My 3-year-old did the same thing for months. I started watching and timing the times that we go poop. Once I got somewhat of a schedule, I made it a point to go to the bathroom and sit with him to read books (about potty training), this way it was fun, as oppose to sitting there just waiting. Once he looked back the first couple times and saw that he could actually go, he was very excited. He has not had an accident since. This was two months ago.
I think what helped was the consistency of potty training being the topic of conversation, we would even read the same books at night :)
Hope this helps!

I had that problem with my son @ 3 1/2 to 4 yrs.  It got to be too much buying little toys to get him to go, so finally I made a "naughty box"  (shoe box labeled on the lid)  I stored it on the fridge.  Whenever he pooped in his pants, I took the toy he was currently playing with and put it up in the naughty box.  The only way he could get a toy out was by pooping in the potty.  Each poop in the potty=one toy rescued.  So if I had 3 of his favorites, I got 3 poops in the potty from him.  It worked great, then he just caught on.  He is 5 now, no more naughty box and no more accidents.  I also bought some fun hand soap that he could only use for poops (pee he used normal hand soap)  I bought the huggies one that the pump (hippo head) would light up and flash for amount of time u are to wash for. You could also purchase some kandoo wipes or any flushable wipes (then put fun character stickers on container (which u could also do to make normal soap, special soap)  only for use with poop.  I would take out pullups period...I know it makes more mess for you (I cannot begin to tell u how many times i was dumping poop out of his underwear or picking it up off the floor...yuck!) but pull ups at this stage make him think what he does is ok.

I actually have the same problem but my little boy is not adopted. He will go pee in the toilet but he will poop in his pants everytime. He doesn't care if we put a pull up or a diaper he just calls it underwear. He goes to Kindergarten and has pooped in his pants there once and I had to go pick him up and bathe him and take him back. I have sat in the bathroom with him for long periods of time reading to him coloring with him and singing songs with him and I am at wits end because he will not poop in the potty...

When your son poops in his pants, make him sit on the toilet for 30 minutes.

It's important to maintain a positive attitude;  ignore the mistakes, poop in the pants, and reward the actions that you want (i.e., sitting on the toilet and having a BM).  Sometimes a simple reward such as a gummy bear works.  Having a child sit on the toilet for 30 minutes after an accident will never succeed -- no child will sit anywhere for 30 minutes (well, maybe in front of a video!)....
And do not do anything to the child's bottom (especially do not try to stimulate BM's with suppositories or enemas -- that will cause worse problems.

well you colud incourage him or get him interested by using a toilet sit of his favorite character and that is how hi should want to start going to the potty and when hi does then you can reward him with a coin. that is what i would use.

You can take him to a doctor to get looked at or you can ask for medicine.

Nicola, I am having the same problem with my son. He is four going on five. He starts kindergarten this September and i am trying to get him to go in the toilet before he starts school. I was wondering if you have resolved the issue and how you did it. He has never gone poop on the toilet and he refuses to use public bathrooms. I can deal with him not using pubic restrooms but the pooping thing is something that needs to be taken care of. It is rather expensive to continue buying pulls ups and i want to get him and my daughter who is 3 out of them for good. Thank you