We report creep and recovery behavior of novel polymers prepared by the cationic copolymerization of fish oil (FO) and conjugated fish oil (CFO) with a number of comonomers using boron trifluoride diethyl etherate as the initiator. The experimental results are compared with classical models of Linear viscoelasticity and structural effects on the creep behavior are examined. The models successfully predict the creep behavior in the static loading range of 0.03-0.07 MPa, together with a retardation time distribution function, suggesting that the materials are linearly viscoelastic under the test conditions. Deviations between experimental results and theoretical predictions are explained in terms of structural effects being controlled by the nature and conjugation of the double bonds in the fish oils, as well as the interactions of the unreacted oils with the crosslinked network structure of the polymers. At high temperatures, the CFO and divinylbenzene copolymers show better creep resistance and higher strain recovery than that of the FO polymers. These results together with those obtained from dynamic mechanical analysis indicate that the polymers may be useful in applications where commercial viscous fish oil systems are not usable. (C) 2000 Elsevier Science Ltd. All rights reserved.