<p>The primary focus of this study is to test the applicability of different paleoenvironmental proxies based on long chain diols, i.e., the LDI as proxy for past SST, the Diol Index as indicator of past upwelling conditions and the NDI as quantitative proxy for nitrate and phosphate concentrations in seawater. The proxies were analyzed in marine sediments recovered at ODP Site 1234, located within the Peru-Chile upwelling system, with a ~ 2 kyr resolution, covering the last 150 kyrs, i.e., encompassing several glacial and interglacial periods. We also generated TEX<sup>H</sup><sub>86</sub> and U<sup><i>K</i>´</sup><sub>37</sub> temperature and planktonic δ<sup>18</sup>O records, as well as TOC and accumulation rates (ARs) of TOC and lipid biomarkers (i.e., C<sub>37</sub> alkenones, GDGTs, dinosterol and loliolide) to reconstruct past phytoplankton production. The LDI-derived SST record co-varies with TEX<sup>H</sup><sub>86</sub>- and U<sup><i>K</i>´</sup><sub>37</sub>-derived SST records as well as with the planktonic δ<sup>18</sup>O record, implying that the LDI reflects past SST variations at this site. TOC and phytoplankton AR records indicate increased export production during the Last Interglacial (MIS 5), simultaneous with a peak in the abundance of preserved <i>Chaetoceros</i> diatoms, suggesting intensified upwelling during this period. The Diol Index is relatively low during the upwelling period, but peaks before and after this period, suggesting that <i>Proboscia</i> diatoms were more dominant before and after the period of upwelling. The NDI reveals the same variations as the Diol Index suggesting that the input of nitrate and phosphate was minimal during upwelling, which is unrealistic. We suggest that the Diol Index should perhaps be considered as an indicator for <i>Proboscia</i> (multiple species) productivity instead of upwelling per se, whereas the NDI likely reflects <i>Proboscia alata</i> productivity, and might therefore not be suitable as a more general paleonutrient proxy.</p>