Blood carboxyhaemoglobin (COHb) was estimated by double wave length spectrophotometry in 58 healthy non-smokers, 27 bidi smokers, 25 cigarette smokers, 25 mixed smokers (all asymptomatic) and 20 symptomatic cigarette smokers. The blood COHb levels were significantly higher among all smoking groups compared to the normal healthy controls (p < 0.001). Among the various smoking groups, the symptomatic cigarette smokers had marginally higher COHb levels compared to the other groups. There was no correlation between the smoking indices and COHb levels and COHb and the packed cell volume of red cells