Our second quarter gross margin of 29% compares quite favorably to our second quarter 2012 gross margin of 37%. Simply put our Q2 2013 gross margin increased by 12 percentage points over the same quarter in the prior year and that was in the phase of an ever challenging reinvestment environment.
I believe that level of progress suggest on a relentless pursuit of operational efficiencies and have in our cost well under control which is producing the results expected. From my perspective, I believe we are heading in the right direction and leveraging our infrastructure quite well.
Let's now turn to our revenue line. As with the first quarter of this year our revenue of $2.2 million for the second quarter of 2013 was again more than double than the second quarter of last year. And either with that significant increase similar to the first quarter of this year, our second quarter 2013 pharma revenue -- even higher and we now have to push out some work related to Companion Diagnosis bridging project that we are doing for GSK. More specifically it would have been higher by approximately $600,000.
Nevertheless, we appreciate that our final business can be lumpy at time and we expect to realize that revenue later in this year.
Let's now turn to our second quarter 2013 Dx revenue , I am pleased to announced that it increased by almost 10% relative to the second quarter of 2012 which we believe is quite good. Again especially in this challenging 2013 reimbursement environment. Relative to the first quarter of this year, revenue was off slightly approximately 2% as we installed new leadership for our field sales organization subsequently fine tuned our territory line and further shifted our selling efforts to lay the groundwork for closing larger accounts based on new programs that we fully expect to implement in the second half of 2013 which I will highlight shortly.
Let me try to put all this into perspective in a broader sense. In the first half of 2013 we were and I might add still are in an aggressive sales and marking building mode and yet our overall revenue increased by nearly 40% over the first six months of 2012 with our pharma revenue more than doubling down the first two quarters of 2012 and RDX revenue increasing by almost 9%. And even with that, had the reimbursement environment not been so challenging uncertain, we believe we would have achieved more growth.
The bottom line is this, first we believe that we are dealing quite well as rapidly changing reimbursing environment and we've led our revenue and gross margin achievements speak for themselves.
Second, I believe we should think of 2012 as the year we built our operational infrastructure into a cost effective and lean group which is producing the result we expected. At 2013 as we are building our sales and marketing organizations with the strong and cost effective selling machine.
I will talk more about our pharma Dx revenue but first let me comment on our bottom line results. We're quite pleased with the bottom line , especially when we compare to where we were just a year ago. Relative to the second quarter of 2012 our second quarter 2013 operating was decreased by over $2.7 million or approximately $1.3 million over a two-fold decrease. In addition, our first half 2013 operating was decreased from over $5.8 million in 2012 to approximately $2.1 million nearly a three-fold decrease.
And in fact let's now turn to what we are doing and we'll continue to do to grow the top-line for our pharma and DX businesses. Beginning with pharma as noted in our previous quarterly conference calls we appreciate that our pharma business relatively lumpy and our goals to mitigate that characteristic as much as possible. We believe the best way to accomplish that goals to continually support our existing customers very well while also selectively adding new business.
I believe we continue to maintain a strong can-do working relationship with our largest Pharma GSK while also providing high service levels to our other customers. That said, in order to selectively grow this part of our company more aggressively we need a decision to build strengthening our existing pharma organization which we did and to also add a field sales person to focus entirely on bringing in new pharma business. Their recruitment process is well underway and I am also pleased to announce that last month we expanded our agreement with Taiho Pharmaceuticals and expect 2013 Taiho revenues of close to and possibly in excess of $1 million in fact based on the agreement just signed we should expect at least $650,000 of additional Taiho revenues in the second half of this year. Looking beyond our large and existing customers we are also pleased to be in discussions with the large pharma and in fact we recently completed a small project with them.
While we are on the topic of large pharma we also added additional work from our largest client named GSK.
Let's now move on the Dx business and as I noted in our last quarterly conference call we have entered a very exciting phase of our Dx business for a number of reasons. The most importantly because we are well along building our sales and marketing partners.