Nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide ($H_2S$) constitute a unique class of mediators which play important roles in maintaining the homeostasis of biological systems. They have many common features: they 1) are small gaseous molecules; 2) freely penetrate the cell membranes to produce cell signaling in a receptor-independent manner; 3) are synthesized endogenously on demand; 4) are rapidly degraded after their release; 5) have specific cellular and molecular targets; 6) work together with each other at many levels. The common roles of NO, CO and $H_2S$ appear to include the regulation of vascular homeostasis and central nervous system function, but they also play additional roles in inflammation. This review will focus on the nature of possible interaction of NO with CO or $H_2S$ in inflammatory states, with a brief description of roles of each of these gaseous molecules in inflammation.