This paper presents further experimental investigations into axial compression of thin-walled circular tubes, a classical problem studied for several decades. A total of 70 quasi-static tests were conducted on circular 6060 aluminium tubes in the T5, as-received condition. The range of D/t considered was expanded over previous studies to D/t=10-450. Collapse modes were observed for L/D=<10 and a mode classification chart developed. The average crush force, F A V , was non-dimensionalised and an empirical formula established as F A V /M P =72.3(D/t) 0 . 3 2 . It was found that test results for both axi-symmetric and non-symmetric modes lie on a single curve. Comprehensive comparisons have been made between existing theories and our test results for F A V . This has revealed some shortcomings, suggesting that further theoretical work may be required. It was found that the ratio of F M A X /F A V increased substantially with an increase in the D/t ratio. The effect of filling aluminium tubes with different density polyurethane foam was also briefly examined.