Vascular casts were prepared using Batson Anatomical corrosion compound, from maximally dilated rat tibialis anterior (TA), extensor digitorum longus (EDL) and soleus (SOL) with normal and limited blood supply (unilateral ligation of the common iliac artery). The weight of casts was expressed as a percentage of muscle wet weight. This value was considered representative for the size of the vascular bed. The value was 2.9 +/- 0.12% (mean +/- SEM) in normal TA, 3.37 +/- 0.15% in EDL and 4.8 +/- 0.43% in SOL. The weight of vascular casts decreased in all muscles to 40% of the values found in the contralateral muscles one week after ligation. Five weeks after ligation, it was about 60% of the control values in TA and EDL, and 80% in SOL. Treatment with torbafylline for one week did not change the weight of the vascular casts. After five weeks the size of the vascular bed was back to control values in EDL and SOL, and only 20% lower than control muscles in TA. This could be attributed to improved development of collateral circulation. Treatment with pentoxifylline improved collateral circulation only in SOL.