I have repaired such holes several times. Using an iron on patch will leave you with a stiff area that will never press-up right. Here's the process a real tailor would use: 1. Use a needle to "grab" two 12-inch individual threads in the excess portion of the interior of the pant material. Typically, that's near the center seam of the back. The trick is that you grab one thread, pull it out slightly until there is what looks like a loop, then use your fingers to gently tug it out from both sides, if necessary loosening it from the remaining material by tugging the ends out with the needle. Â If the thread breaks, you pulled too hard. Try again with the adjacent thread. 2. Once you've got two good threads, insert one of these threads into a fine needle. 3. From the INSIDE of the pants, starting above the hole and going to below it, run parallel back and forth stitches in an oversize square until you cover over the hole. You want to grab the pant fabric with each stitch, but not go through it showing a stitch on the outside. 4. Again from the INSIDE of the pants, take the second thread and repeat the process at a right angle to the first rows of thread. Only this time, have the point of the needle go over and then under each alternate thread, like you're weaving a basket. This second square should again be oversize. In essence, you're doing what's called "darning." 5. Do this in good light, wearing glasses if necessary. When you're done, examine the pants from the outside. The result should be a slightly puckered version of the original fabric. Press and the puckering will disappear. Congratulations: you have just "darned" or "rewoven" the hole. The limit on this technique is about 1/4 inch. For larger holes, you need a patch piece of fabric woven in, but that's an order of magnitude more difficult. 6. If all this seems hopelessly out-of-reach, find a good drycleaner who sends out "reweaving". You'll pay about $50 per hole to have it done by a pro.