Peculiarities of liquid systems constructed from line objects (like polymers, or worm-like micelles) are investigated. Namely the static structure function for nematic polymers are calculated. The role of free ends of chains is discussed. Nonlinear hydrodynamic equations are derived by means of the Poisson brackets method. The linear spectrum of eigen-modes is found. Thermal fluctuations lead to logarithmical contributions to viscosity coefficients. Very special case is line liquids constructed from long worm-like micelles.