The effect of retinoic acid on the differentiation of a human retinal pigment epithelium‐derived cell line ARPE‐19 was studied. Differentiation of ARPE‐19 cells is delayed by retinoic acid. The minimum all‐trans‐retinoic acid concentration needed for delay of ARPE‐19 differentiation is 1 μM. A delay of differentiation was also observed using 1 μM 9‐cis or 13‐cis‐retinoic acid. Differentiation at the molecular level was studied by analyzing transcription of two RPE‐marker genes, RPE65 and peropsin. In the presence of 1 μM retinoic acid the onset of transcription of both genes was delayed by 2–3 weeks. We conclude that alltrans‐, 9‐cis‐, and 13‐cis‐retinoic acid delay differentiation of ARPE‐19 cells into cells that phenotypically resemble cells from the human retinal pigment epithelium.