The lipid composition of chlorotic leaves of Pisum sativum L. cv. Kelvedon Wonder, developed under iron‐deficiency was determined and compared to similar material developed under normal nutrient conditions. All lipid classes were affected by iron‐deficiency but to different extents, and thylakoid lipids were more affected than non‐thylakoid lipids. The most striking results concerned changes in the fatty acid content of the main polar lipids. The linolenic acid of the galactolipids decreased to the benefit of more saturated fatty acids, mainly linoleic acid. In phosphatidylglycerol, the proportion of Δ3‐trans‐hexadecenoic acid decreased. Using radioactive acetate, lipid synthesis was investigated. Desaturation leading to linoleic acid was less affected by iron‐deficiency than desaturation leading to Δ3‐trans‐hexadecenoic and linolenic acids.