Sustained release (SR)-gastroretentive dosage forms (GRDF) enable prolonged and continuous input of the drug to the upper parts of the gastrointestinal (GI) tract and improve the bioavailability of medications that are characterized by a narrow absorption window. A new strategy is proposed for the development of gastroretentive dosage forms for ofloxacin preferably once daily. The design of the delivery system was based on the sustained release formulation, with floating and swelling features in order to prolong the gastric retention time of the drug delivery systems. Different polymers, such as psyllium husk, HPMC K100M, crospovidone and its combinations were tried in order to get the desired sustained release profile over a period of 24 h. Various formulations were evaluated for buoyancy lag time, duration of buoyancy, dimensional stability, drug content and in vitro drug release profile. It was found that dimensional stability of the formulation increases with the increasing psyllium husk concentration. It was also found that in vitro drug release rate increased with increasing amount of crospovidone due to the increased water uptake, and hence increased driving force for drug release. The optimized formulation was subjected to stability studies at different temperature and humidity conditions as per ICH guidelines. In vivo studies were carried out for the optimized formulation in 24 healthy human volunteers and the pharmacokinetic parameters of developed formulations were compared with the marketed once daily (Zanocin) formulation. Based on the in vivo performance in a parallel study design in healthy subjects, the developed formulation shows promise to be bioequivalent to the marketed product (Zanocin). The percent relative bioavailability of developed formulation was found to be 97.55%. © 2005 Elsevier B.V. All rights reserved.