In situ gelling systems are extensively investigated for nasal administration of drugs. The selection of constituents (primarily polymers) and their concentration in in situ gelling systems affect properties of gel formed in contact with the nasal mucosa. The rheological properties of the gel define the retention time and the release profile of the drug at the site of administration, and thus the bioavailability of the drug at the site of action. The aim of this work is to prepare in situ gelling suspensions of fluticasone propionate (0.1%, w/w) differing in polymer composition and drug to suspending agent ratio, and to determine the influence of these formulation parameters on the rheological properties of the gels that are formed at the application site. Pectin (0.5-0.7%, w/w) and gellan gum (0 or 0.2%, w/w) were used as constitutive polymers as they gel in contact with cations in the nasal fluid. Sodium hyaluronate (0 or 0.05%, w/w) was also used as constitutive polymer. Polysorbate 80 (0.01 or 0.05%, w/w) was used as the suspending agent, while mannitol (4.0%, w/w) was used as isotonizing agent. In situ gelation of prepared fluticasone propionate suspensions was simulated by mixing them with an artificial nasal fluid in a volume ratio 1:1. Sol-gel phase transition of the prepared systems was observed instantly. For all gels formed, values of storage modulus were greater than the values of the loss modulus, in range of angular frequencies employed (0.1–100 rad s-1 ). Viscoelastic moduli values and shear stress, as indicators of gel strength, increased with increasing pectin content and especially with increasing gellan gum content in the formulation. No significant effect of sodium hyaluronate and polysorbate 80 on gel strength was observed. Formed gels are characterized by higher viscosity than the sol phase. The viscosity of the gels decreased with increasing the shear rate, suggesting a pseudoplastic behaviour of the gels. The results of this thesis contribute to the directed development of in situ gelling fluticasone propionate suspension for nasal administration.