In 1976 Ramanathan et al introduced a unilimb circle circuit connecting the CO2, absorber and dome valve. A coaxial breathing circuit, Mera F Type breathing circuit, is very light in weight, compact and it can be made any length. This circuit can be used as a circle system, rebreathing or non-rebreathing system and it can be applicable to both pediatric and adult anesthesia. This circuit is easily adaptable to humidification and pollution control devices. It is especially suitable for any kind of surgical procedures including head, neck and others requiring any awkward positions. A clinical study of this circuit was done in 30 cases and compaired with 18 cases using the coventional circuit. Fresh gas flow, tidal volume and respiratory rate were 4 L/min(02:2 L/min., N2O:2L/min.),10 ml/kg and 12-14/min respectively. Controlled ventilation using a volume preset ventilator was used in all cases. After induction, radial artery cannulation with a 20 G angiocatheter was done and blood gas analysis was performed at 30, 60 and 90 minutes respectively. The blood gas analysis was found satisfactory in either the conventional or the Mera F circuit system.