Essential oils were isolated by hydrodistillation from the stems plus leaves, inflorescences and seeds of Pimpinella affinis Ledeb. individually. The plants were collected from Khojir and Chaloos (north-east and north of Tehran province, respectively). The yields of stem plus leaf, inflorescence and seed oils for the Khojir samples were 0.04%, 1.98% and 5.33% w/w and for the Chalous samples were 0.37%, 1.74% and 4.05% w/w, respectively. Limonene is a major constituent in the inflorescence and seed oils of the Khojir (47.9% and 90.5%, respectively) and Chalous samples (37.8% and 70.8%, respectively), whereas it was found in the stem plus leaf oil of the Khojir and the Chalous samples in low amounts (1.4% and 0.8%, respectively). γ γ γ γ γ -Terpinen-7-al is the major constituent in the stem plus leaf and inflorescence oils of the Khojir (69.9% and 37.6%) and Chalous samples (72.8% and 49.1%), but was not found at all in the seed oils. Caryophyllene oxide (9.1%) was found in the stem plus leaf oil of the Khojir sample, and methyl eugenol (9.7%) and (E)-nerolidol acetate (9.1%) in the seed oil of the Chalous sample.