The investigation of a dilute solution of phantom ideal ring polymers and ring polymers with excluded volume interactions (EVI) in a good solvent confined in a slit geometry of two parallel repulsive walls and in a solution of colloidal particles of big size was performed. Taking into account the correspondence between the field theoretical φ 4 O(n)-vector model in the limit n → 0 and the behaviour of long-flexible polymers in a good solvent, the correspondent depletion forces and the forces which exert phantom ideal ring polymers and ring polymers with EVI on the walls were obtained in the framework of the massive field theory approach at fixed space dimensions d=3 up to one-loop order. Besides, taking into account the Derjaguin approximation, the depletion forces between big colloidal particle and a wall and in the case of two big colloidal particles were calculated. The obtained results indicate that phantom ideal ring polymers and ring polymers with EVI due to the complexity of chain topology and for entropical reasons demonstrate a completely different behaviour in confined geometries compared with linear polymers.Key words: colloidal systems,critical phenomena, polymers, phase transitions PACS: 64.70.pv, 61.25.he, 67.30.ej, 68.35.Rh, 64.70.qd As it was shown in a series of the atomic force spectroscopy (AFM) experiments [1, 2], biopolymers such as DNA very often present a ring topology. Such a situation takes place, for example, in the case of Escherichia coli (E.coli) bacteria with a chromosome which is not a linear polymer, but has a ring topology [3]. The biopolymers of DNA of some viruses such as bacteriophages λ that infect bacteria oscillate between linear and ring topology [4,5]. The physical effects arising from confinement and chain topology play a significant role in the shaping of individual chromosomes and in the process of their segregation, especially in the case of elongated bacterial cells [6]. The behaviour of linear ideal and real polymers with excluded volume interaction (EVI) in a good solvent confined in a slit of two parallel repulsive [7,8], inert or mixed walls is well understood [8]. Unfortunately, the physics of confined ideal ring polymers and ring polymers with EVI effects is still unclear. Ring polymers with specified knot type were chemically synthesized a long time ago [9]. Ring topology of polymers influences the statistical mechanical properties of these polymers, for example the scaling properties [10,11] and shape [2,12,13] because it restrains the accessible phase space. An interesting point which was confirmed by numerical studies in [14] is that longer ring polymers are usually knotted with higher frequency and complexity. In [15], it was established that ring polymers with more complex knots are more compact and have a smaller radius of gyration and this decreases their ability to spread out under confinement. The results of Monte Carlo simulations performed in [16] suggest that the knotted ring polymers will exert higher entropic forces on the walls of the confini...