<p>The boron isotopic composition (δ<sup>11</sup>B) of benthic foraminifera provides a valuable tool to reconstruct past deep-water pH. As the abundance of monospecific species might be limited in sediments, microanalytical techniques can help to overcome this problem, but such studies on benthic foraminiferal δ<sup>11</sup>B are sparse. In addition, microanalytics provide information on the distribution of δ<sup>11</sup>B at high spatial resolution to increase the knowledge of e.g. biomineralization processes. For this study, we investigated the intra- and inter-shell δ<sup>11</sup>B variability of the epibenthic species <i>Cibicidoides wuellerstorfi</i>, which is widely used in paleoceanography, by secondary ion mass spectrometry (SIMS) and femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS). While the average δ<sup>11</sup>B values obtained from these different techniques agree remarkably well with bulk solution values to within ± 0.1 ‰, a relatively large intra-shell variability was observed. Based on multiple measurements within single shells, the SIMS and LA data suggest median variations of 4.8 ‰ and 1.3 ‰ (2σ), respectively, where the larger spread for SIMS is attributed to the smaller volume of calcite being analyzed in each run. When analytical uncertainties and volume-dependent differences in δ<sup>11</sup>B variations are taken into account for these methods, the intra-shell variability is presumably in the order of ~ 3 ‰ and ~ 0.4 ‰ (2σ) on a ~ 20 µm and 100 µm scale, respectively. In comparison, the δ<sup>11</sup>B variability between shells exhibits a total range of ~ 3 ‰ for both techniques, suggesting that several shells need to be analyzed for accurate mean δ<sup>11</sup>B values. Based on a simple resampling method, we conclude that ~ 7 shells of <i>C. wuellerstorfi</i> must be analyzed using LA-MC-ICPMS to obtain an accurate average value within ± 0.5 ‰ (2σ) to resolve pH variations of ~ 0.1. Based on our findings, we suggest to prefer the conventional bulk solution MC-ICPMS over the in-situ methods for e.g. paleo-pH studies. However, SIMS and LA provide powerful tools for high-resolution paleoreconstructions, or for investigating ontogenetic trends in δ<sup>11</sup>B, possibly due to <q>vital effects</q> during chamber formation.</p>