Measurement of chlorophyll-a can be considered important to investigate the primary production of an ecosystem. This study aimed to investigate chlorophyll-a concentration, primary production and the factors affecting them in Shadegan Wetland located in Khouzestan Province - Iran. Sampling for measuring (NO₃, PO₄, BOD₅, DO, pH, EC, salinity, temperature) was performed seasonally at five sampling stations of the wetland (Canal, Ragbeh, Khoroosi, Mahshahr and Atish), from March 2013 – through February 2014. Results showed that chlorophyll-a concentrations in Canal station were significantly higher than that in the other stations; however, there were no significant differences among the other sampling stations (p>0.05). The maximum and minimum primary production (and chlorophyll-a) (62, 1.14 mg/m³) were observed at Canal and Ragbeh stations, respectively. Annual average chlorophyll-a concentration was 10.28 mg/m³, and there was no significant seasonal difference (p>0.05). The maximum value of chlorophyll-a was observed in the fall (29.63 mg/m³), whereas, the minimum value was related to the spring (4.07 mg/m³). Among the water physicochemical parameters, nitrate had a significant effect on chlorophyll-a concentrations. According to trophic state index (TSI), Shadegan Wetland is mesotrophic in the spring and winter, whereas it is eutrophic in the summer and fall. Overall, the lake is suitable for warm water species.