The integration joint assembly includes an integration joint body (10) having a through bore (16), the body being for connection with a riser system. The integration joint assembly permits a tubular work string (50; 54) to pass there through such that there is an annulus created between the inner through bore (16) of the integration joint body (10) and the outer surface of the tubular work string (50; 54). The integration joint body (10) can also include at least two (300, 200) and more preferably three sealing devices (300, 200, 100) within its through bore (16). A method of drilling is also described as including the steps of installing an integration joint assembly in a riser string and running a tubular work string (50; 54) through the through bore (16) thereof.