A new design for lung fixation at a constant transpulmonary pressure is described. The head pressure of the apparatus can easily be set in a range from 15 to 95 cm H2O and maintained at a constant level through the recirculation of the fixative fluid. Moreover, the dimensions of the device are smaller than those previously reported. To analyze the efficiency of the equipment the estimated total post-fixing lung volume (TLV) in 12 surgically obtained lung specimens was calculated and compared with helium single-breath total lung capacity measurements (TLCsb). The TLV/TLCsb ratio was 102 +/- 5%. In addition, TLV was related to predicted TLC values (TLCpred) from different reference equations. The TLV/TLCpred ratios ranged from 89 to 99%. Estimated volumes of formalin fixed lungs did not show significant differences to those obtained by TLCsb measurements (p = 0.49). Consequently, it can be concluded that the fixation procedure performed with this device does not produce changes in air space dimensions of surgically obtained lung specimens. Moreover, the variability in TLV/TLC ratios depends upon either the technique of TLC measurement or the set of predicted values used.