Of 162 patients aged 27-28 years, referred during a 12-month period to the Dept. of medicine, Norrköping Central Hospital, for deep vein thrombosis (DVT), 102 (63 per cent) were treated as out-patients with the low molecular weight heparin preparation, dalteparin (Fragmin), given subcutaneously at a standardised daily dosage of 200 U/kg. No serious thrombotic events were reported. The frequency of post-thrombotic symptoms at six months did not differ from that among hospitalised patients on standard heparin treatment. Thus, the proportion of DVT patients treated as in-patients was reduced by 50 per cent, despite a 33 per cent increase in the number of referrals for DVT during the period. At follow-up, almost 90 per cent of the patients expressed satisfaction with the out-patient routines.