Progressive ageing associates with an increasing incidence of cardiac dysfunction and arrhythmias. Such problems are likely to be contributed to by changes in cardiac intracellular calcium regulation but findings are often inconsistent possibly due to a mix of sample types, ages, species and genders studied. This study used quantitative PCR (qPCR) to assess expression of mRNA for proteins involved in cellular calcium regulation across the wall of the left ventricle (LV) in both genders at three age points: young (6 months), adult (12 months) and old (24 months). C57Bl6 mice (n=6 for each gender at each age) were euthanised by cervical dislocation and samples from the sub-endocardial (endo) and sub-epicardial (epi) LV free wall dissected. Following mRNA isolation, samples were subjected to qPCR with results normalised to GAPDH mRNA abundance. Data were assessed by Pearson correlation or ANOVA. The effects of ageing on key transcripts are summarised in Table 1. The combined data showed significant negative correlations between age and mRNA expression for the L-type Ca2+ channel, D-type Ca2+ channel, the cacna1h isoform of the T-type Ca2+ channel, ryanodine receptors (RYR), phospholamban (PLB) and calcium-calmodulin dependent protein kinase 2 (CAMK2D). Analysing individual genders these age-associated declines were common to males and females for PLB but all other correlations were significant in males only, aside for that of the D-type Ca2+ channel decline which correlated with age only in females. No regional heterogeneity of changes was observed in females. In contrast in males the cacna1h isoform of the T-type Ca2+ channel, and CAMK2D fell significantly with age in endo only, whilst a rise in calsequestrin mRNA was unique to this region. RYR mRNA fell in both endo and epi whilst PLB mRNA fell significantly only in epi. SERCA2a mRNA remained unchanged, as did that for the cacna1g isoform of the T-type Ca2+ channel, sarcolemmal Ca2+ pumps (PMCA1 and 4), sodium-calcium exchanger and sodium-potassium pump α1 isoform. In conclusion, ageing has heterogeneous effects on mRNA transcript abundance for key regulatory proteins dependent on gender and ventricular region. The majority of changes were observed in the male heart alone where increasing heterogeneity of expression across the LV wall may predispose to dysfunction and arrhythmias.