The calundula (Calendula officinalisL.) is an important medicinal plant that is used as sudorific, blood refiner, blood sugar reducer and also used for anti-inflammatory skin problems. In order to investigate the effects of different nitrogen application rates on growth, flower and seed yield of calendula, a field experiment was conducted based on Randomized Complete Block Design (RCBD) with four replications at the Agricultural Research Station, Azad University of Torbat-e-Jam, Iran, during growing season of 2008-2009. Nitrogen rates were 0, 30, 60 and 90 kg N. ha-1. Plant criteria such as seed yield, biological yield, flower yield and harvest index (HI) were measured accordingly. The results showed that the effects of nitrogen rates were significant (p≥0.01) on seed yield, biological yield, flower yield and HI. The highest and the lowest seed yield and flower yield were observed in 60 (71.37 and 119.27 g.m-2) and 0 kg N. ha-1 (29.67 and 63.70 g.m-2), respectively. It was concluded that nitrogen increased the growth and yield of calendula.

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