Defining cyclical characteristics is an essential part of soil behavior research. Especially when it comes to soil susceptible to liquefaction in the area where frequent earthquakes occur. Sand layers located near the surface are usually less compacted and have smaller overburden effective stress. For this reason it is more likely for liquefaction to take place. Apart from earthquakes, such research can also contribute to projects such as offshore wind turbine foundations, subsea pipelines and slope stability analysis. Dynamic soil properties, such as stress and strain properties, have been recognized as crucial in many aspects of design. There are several types of geotechnical engineering problems associated with dynamic loading, and with the help of laboratory tests it is possible to make a reproduction of real events with fairly high accuracy. In this way, numerous parameters, physical and mechanical characteristics of the soil can be established and used to improve the design and construction of buildings. The subject of this paper is determining the cyclic behavior of uniform sand in drained and undrained conditions at low effective stresses. The tests were performed in a dynamic triaxial apparatus on sand samples with a medium relative density (50%). The experiments were conducted using strain-control test method in drained and undrained conditions for low effective stresses (σ₀ = 10 kPa, σ₀ = 25 kPa i σ₀ = 50 kPa) and different frequencies (0.1, 0.2 and 0.5 Hz). The paper presents the obtained results and compares them with the existing literature. Most of the results confirm that the examined material behaves in accordance with the published works. However, due to data scatter, some results were not used. In general, the lower the effective stresses, combined with smaller deformations, the greater the data scatter. Based on the obtained results, models of cyclic behavior of sand at low effective stresses and different frequencies were defined. The models were derived for trends of increasing normalized pore pressure rᵤ and volume strain ϵᵥ,ₘₐₓ using discrete points. Trend lines were determined using the nonlinear least squares model. For verification, but also for further investigation of small effective stresses, it is necessary to calibrate the dynamic triaxial apparatus and/or test the material in the device suitable for small effective stress and deformation experiments, for example the resonant column.