Summary Two cases of spontaneous haemothorax have been described and the literature has been reviewed briefly. One case conformed to the accepted pattern of acute onset, period of recovery, recrudescence of pain and dyspnoea with signs of internal haemorrhage and physical signs of pleural effusion. The second case developed gradually and was associated with low backache. The cause was considered to be the same in both cases, namely, spontaneous pneumothorax followed by continued haemorrhage from the parietal adhesion stump. Treatment by air replacement in one stage was effective in these cases and their convalescence was uneventful.