The effect of the Forced Expiration Technique (FET) with or without Postural Drainage (PD) was examined in eight adults with cystic fibrosis. On four mornings the patients followed a 30-min physiotherapy session consisting in a randomized order of either FET in a sitting position following a night of horizontal sleep ("FET"), or FET in a postural drainage position following sleep including postural drainage ("FET/PD"). The lung function parameters studied did not change during either of the two treatments. Sputum yield over 22.5 h before the physiotherapy sessions and over 24 h increased with PD during sleep in patients with more than 30 g of sputum per 24 h (p less than 0.05). PD during the treatment sessions did not further increase sputum production. This study indicates that sleeping head-down improves expectoration in patients with copious sputum. PD during FET is not needed after sleeping in the head-down position.