This study evaluates the cost-effectiveness of OMACOR treatment as a standard prevention measure post-MI in the UK. A cost-effectiveness model was developed based on the GISSI-P trial, combining a survival and a Markov model, over a lifetime period. The base case results for OMACOR, at 4 years and over a lifetime, respectively, were: Cost per QALY gained: £3,717 and £15,189; cost per life years gained (LYG): £2,812 and £12,011. The cost per death avoided at 4 years was £31,786. Deterministic and probabilistic sensitivity analyses did not change the base case results substantially. The use of OMACOR as a standard post-MI prevention treatment seems warranted in the UK, both on the basis of its efficacy, which is in addition to other prophylactic treatments as evidenced by the results of the GISSI-P trial, and on cost-effectiveness grounds – both at 4 years and over a lifetime's time-horizon, using the current cost-effectiveness thresholds.