Modern patients are well informed and often demand posterior ‘aesthetic’ restorations. To the patient the type or brand name of the product which is used is irrelevant, as long as the results are aesthetic, affordable, and can be placed quickly and with minimal personal discomfort and post-operative problems. One of the most affordable aesthetic options is a directly-placed, composite restoration. The overall success of such restorations not only depends on the clinical situation, but also on the expertise of the dentist and the time he/she is willing to spend for the fee he/she will be paid. Placing a successful posterior composite restoration is a technique-sensitive, time-consuming art and any shortcuts used during the placement of such a restoration is sure to lead to post-operative problems. It is well known that post-operative sensitivity is one of the major problems regarding this type of restoration. This article will address various factors that could contribute or lead to post-operative sensitivity.