In acute carbon monoxide intoxication the presence of altered consciousness
, ranging from transient loss of consciousness to coma, represents a poor p
rognostic factor and modifies the approach to therapy. Transient loss of co
nsciousness is, as a rule, contemporaneous to the exposure, generally occur
ring at the scene of the intoxication. We report an unusual case of delayed
transient loss of consciousness, occurring in the absence of any other evi
dent aetiology, in one member of an orchestra composed of 110 members after
a mass carbon monoxide poisoning.