In this study, the effects of panel photobioreactors with different nutrient mediums and different light path lengths on Chlorella vulgaris cultures were investigated. Rapid cell growth was detected in the Jaworski nutrient medium (60.8 x 10(6) cells mL-1). In the F/2 nutrient medium, the cell number was recorded as 1.37 x 10(6) cells mL(-1) on the 11th day. Dry weight of cultures grown in Jaworski and F/2 nutrient media were measured as 0.46 gL(-1) and 0.13 gL(-1) at the end of 11 days, respectively. At the experiments in glass panel bioreactor, the highest cell number was found on the 31st day (230 x 106 cells mL(-1)) in a bioreactor with 1 cm light path length. Whereas, the highest cell numbers was found as 90 x 106 cells mL(-1) in glass panel bioreactors with 3 cm and 5 cm light path length. The maximum dry weights for bioreactors with 1, 3 and 5 cm light path lengths were determined as 3.6 gL(-1), 2.8 gL(-1) and 2.4 gL(-1), respectively. It was also determined that chlorophyll a values of Chlorella vulgaris on the panels bioreactors decreased over time. Moreover, the inversely proportion between growth rates and the chlorophyll-a values was observed.