Our previous studies have shown that the influence of the illuminating source used for colour vision examination on the intended function of the test is very test dependant, some being relatively unaffected by source characteristics while others can be significantly affected. The effects can even differ between the plates of one pseudo-isochromatic plate test set. In addition, in previous studies we have considered a large range of sources on one test at a time. For this study the emphasis is on four fluorescent tube sources, all of which meet the requirements of the CIE method for assessing the quality of daylight simulators. The colour vision tests include sorting tests (the D-15 tests [Standard, Lanthony Desat and Adams Desat]), the Lanthony New Colour Test and the FM100 Hue Test, pseudoisochromatic plate tests (Ishihara, Standard Pseudoisochromatic Plates Volume 1, Hahn New Colour Test and Lanthony Tritan Album) and a matching test (TCU Test). Two examples are quoted here. The tests were assessed on the basis of alignment of the colours of the tests to protanopic and deuteranopic confusion axes and, where appropriate, to the tritanopic confusion axis. The data and analysis indicate that the four fluorescent tubes are essentially equivalent.