Purpose: to investigate functional performance in relation to muscle function during first year after stroke. Methods: Maximal voluntary isometric torques of knee extensors (MVTe) and flexors (MVTf) were obtained in 14 patients with subacute stroke (bilaterally) 3.5±2 months after stroke and 3 (n=8), 6 (n=5) and 12 months (n=3) thereafter and in 12 age-matched able-bodied subjects. Maximal triplet response (intrinsic muscle strength), maximal rate of torque development (MRTD) and degree of voluntary activation of knee extensors were estimated. Patients performed 7 tests of functional performance. Results: In the paretic lower limb (PL), all parameters significantly (0.494<|r|<0.909) improved during all follow-ups. In the non-paretic lower limb (NL) most improvement occurred within the first 3 months. For NL and PL, MVTe improved 5 and 16%, respectively MVTf 3 and 20%, triplet 0 and 13%, activation 8 and 9%, MRTD 16 and 61%. Significant correlations (0.460<|r|<0.906) were found between all tests of functional performance and all muscle parameters of PL and all parameters (0.454<|r|<0.873) but triplet and MRTD of NL. Conclusion: All strength parameters correlated significantly with functional performance. Therefore, it is recommended to investigate the role of strength training of both legs during at least the first year of stroke.