PURPOSE: To analyze the effects of resistance exercise (RE) on the muscle strength, leg loading, functional capacity and balance of older women with knee osteoarthritis (OA) and total knee arthroplasty (TKA). METHODS: Fifteen older women with (OKG; N = 7) and without (OG; N = 8) knee OA and TKA, and eight young healthy women (YG) have their muscle strength (1-RM strength), leg loading during sit-to-stand, stand balance (bi- and unilateral) and functional capacity (6-min walking, sit-to-stand, rising from floor, and stair-climbing tests) analyzed before and after twelve weeks of a twice-a-week whole body (9 exercises) RE program (2 sets of 8-12 repetitions at 60-70% of 1-RM) RESULTS: Reduced baseline functional capacity, unilateral balance and 1-RM strength, and greater baseline lower-extremity 1-RM strength and sit-to-stand loading deficits were observed in OKG than both OG and YG (P < 0.05). After RE, 1-RM strength increased in all groups (P < 0.001). RE also improved (P < 0.05) sit-to-stand time (14.8 ± 7.4%), rising from floor time (13.2 ± 9.8%) and 6-min walking distance (17.8 ± 9.8%) in OKG and OG, and stair-climbing time (13.3 ± 9.4%), unilateral balance (75.2 ± 27.9%), and sit-to-stand rising index (12.3 ± 6.1%) and loading distribution (57.6 ± 17.2%) only in OKG. Post-RE muscle strength improvement was greater (P < 0.05) in OKG (51.1 ± 7.3%) than OG (33.8 ± 14.8%) and YG (25.8 ± 7.6%), and 6-min distance improvement was greater (P < 0.01) in OKG (13.7 ± 5.8%) than YG (22.6 ± 11.8%). OKG also showed greater lower-extremity 1-RM strength increase (P < 0.01) in the leg with OA (67.2 ± 11.6%) than TKA (38.9 ± 6.0%), which resulted in reduction (P < 0.001) of 1-RM strength (23.4 ± 7.4 vs. 10.8 ± 7.7%) and sit-to-stand loading (21.1 ± 4.9 vs. 9.3 ± 5.2%) deficits between legs. With the improvements, OKG showed post-RE 6-min walking distance, sit-to-stand rising index, and trunk and upper-extremity strength levels similar than OG. OKG post-RE 1-RM strength of the TKA lower-extremity, but not OA lower-extremity, was also similar than OG lower-extremity 1-RM strength. CONCLUSIONS: Resistance exercise was an effective intervention to improve muscle strength, leg loading, functional capacity and balance of older women with knee osteoarthritis and total knee arthroplasty.