Light intensity and quality are one of the most important environmental factors influencing crop physiology and biochemistry. Light is a prerequisite for performing photosynthesis by which light energy is converted into chemical energy and energy-rich organic compounds and oxygen are formed. For this reason, it is necessary to ensure appropriate lighting conditions when growing plants in protected areas. In controlled conditions, ensuring optimal light intensity requires economically significant allocations, so it is important to use enough light, but at minimal cost. This study was conducted under controlled conditions (in the growth chamber) on Dark opal basil variety. The treatments were represented by three different light intensities: 100 μmol m-2 s-1, 200 μmol m-2 s-1 and 300 μmol m-2 s-1. The intensity and spectral composition of the light was determined using a LI-180 spectrometer. Gas exchange parameters (photosynthesis intensity, transpiration intensity, stomatal conductivity, and mesophilic CO2 concentration) were measured using a portable LI-6800 gas exchange measuring device. Water efficiency and light efficiency were calculated from the gas exchange parameters. In the conditions of the strongest illumination (300 μmol m-2 s-1), the highest intensity of photosynthesis and the highest efficiency of light utilization were determined which is the result of adaptation of plants to cultivation at higher light intensity. Higher intensity of photosynthesis will result in bigger biomass, that is, higher yields of plants grown in controlled conditions.