Coiled tubing injector head with chain guides

In an injector head (30) for handling tubing for insertion into and retrieval from a wellbore, a non-gripping portion of the path (22) of each chain loop (12), which is otherwise susceptible to oscillations when running in at least certain conditions, is constrained by a chain guide (44). The chain guide allows the chain to move freely as it is driven by the sprockets (16) in a loop, but dampens or prevents development of oscillations in the chain loop (12) when moving along one or more sections of its path in which it is not otherwise be pressed against tubing or constrained by sprockets or tensioners.