The presence of lipids in animal tissues can influence the interpretation of stable isotope data, particularly in lipid‐rich tissues such as the skin and muscle of marine mammals. The traditionally employed chloroform:methanol delipidation protocol has the potential to alter δ¹⁵N values in proteinaceous tissues. Our objective was to determine whether cyclohexane is an alternative extraction method, effectively removing lipids without altering δ¹⁵N values. Kidney, liver, muscle, and skin samples were collected from beach‐cast Sowerby's beaked whales (Mesoplodon bidens ). Control subsamples were processed without delipidation extraction, and duplicate subsamples were extracted with either chloroform:methanol or cyclohexane. δ¹³C, δ¹⁵N, and C:N values were determined by continuous‐flow elemental analysis isotope ratio mass spectrometry. Paired Wilcoxon tests were used to evaluate the change in isotope ratios after extraction, and unpaired Wilcoxon tests were used to evaluate difference in isotope ratios between extractions. Cyclohexane is an effective delipidation technique for tissues with low and moderate lipid content. Chemical delipidation influenced δ¹⁵N values; extracted samples generally showed an increase in δ¹⁵N values which varied from 0.0‰ to 1.7‰. Chloroform:methanol extraction resulted in alterations to δ¹⁵N values greater than the analytical precision for all analyzed tissues. Changes to δ¹⁵N values after cyclohexane extraction were at or near the analytical precision in liver and muscle but greater than the analytical precision for kidney and skin. We recommend processing duplicate subsamples for stable isotope analysis, one with and one without extraction in order to obtain accurate values for each isotope ratio. Prolonged chemical extractions are not necessary to effectively remove lipids. When samples are limited, we suggest using cyclohexane for tissues with low or moderate lipid content, and chloroform:methanol for lipid‐rich tissues.