It has been shown that the incidence of recurrent stenosis following successful percutaneous transluminal coronary angioplasty (PTCA) is correlated with serum Lipoprotein(a) [Lp(a)] levels. The aim of the present study was to examine the influence of Lp(a) on restenosis after primary successful femoropopliteal PTA. One hundred and thirty nine consecutive patients with peripheral arterial occlusive disease (PAOD) and successful femoropopliteal PTA were studied. Follow-up included clinical examination and non-invasive laboratory testing (pulse volume recordings, ankle-brachial arterial pressure measurement) in every patient before and after 1, 3, 6 and 12 months following intervention. Duplex sonography was performed 1 year after PTA. Suspicion of restenosis (> or = 50% diameter reduction) was verified by angiography. Lp(a) was determined using ELISA technique (mg/dl). Twelve months after successful PTA no restenosis was found in 82 patients (59%: group A). The one-year recurrence rate of 41% (group B) was due to significant restenosis in 35 patients (25%) and reocclusion in 22 patients (16%). The corresponding mean values +/- S.E.M. for Lp(a) were as follows: group A, 28 +/- 5.3; group B 59 +/- 11 (P < 0.01). Women showed a higher frequency of recurrences (55%) versus men (30%, P < 0.01) also corresponding with a high Lp(a) level (51.8 +/- 8 versus 32.7 +/- 5; P < 0.05). Furthermore Lp(a) aggravated the well known increased risk for recurrence in multiple stenoses or occlusions of > or = 5 cm in length. There were no significant differences between groups A and B with respect to age, diabetes, hyperlipidaemia, obesity and cigarette smoking. The results support the view that Lp(a) is an independent risk factor for recurrence after PTA in the femoropopliteal area. It might also be a causal basis for the higher incidence of recurrences in female PAOD patients.