The present invention relates to pharmaceutical formulations containing a combination of specific high-molecular weight hyaluronic acid derivatives and chondroitin sulfate to be used in the treatment of osteoarthritis, of subchondral damage, osteoporosis, synovitis, tenosynovitis, tendinitis, tendinosis, as an intra-articular washing liquid and as a viscous substitute of synovial fluid following osteochondral surgery. These formulations are also suitable for the treatment of interstitial cystitis.