This study is among the first to take known results in pension accounting and use a sample of UK listed FTSE 100 companies to show that the results are mostly the same as in previous research (on the US companies) into associations between pension accounting information and firm value. We investigate the association between published pension accounting information and the market value of a sample of UK listed FTSE 100 companies in the ten-year period 2006 to 2015. We analyse UK listed firms that report under the IFRS accounting framework (IAS 19), which is a contribution to earlier literature that concentrated on US listed firms that report under the US (FASB) accounting framework that has significantly different pension accounting rules to the IFRS accounting framework. Moreover, the analysis is conducted on a sample of firms that used the method of immediate recognition of actuarial gains and losses in other comprehensive income (or the ‘Fair Value OCI method’) even before mandatory adoption of this method from 2013. We employ a static panel regression analysis on a sample of 70 companies. Empirical findings suggest that there is an association between pension accounting information and firm value, but in some cases, there is less association than there is between other types of accounting information and firm value. Core earnings are value relevant but overall pension earnings (net) are not value relevant although pension costs, pension interest expense and pension income have an association with firm value. Balance sheet numbers have less association with firm value than is the case for core earnings, pension costs, pension interest expense or pension income.