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 6 10 anda mode classi5cation chart developed. The average crush force, FAV, was non-dimensionalisedandan empirical formula establishedas FAV=MP = 72:3(D=t)0:32. 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 andour test results for FAV. This has revealedsome shortcomings, suggesting that further theoretical work may be required. It was found that the ratio of FMAX=FAV increasedsubstantially with an increase in the D/t ratio. The effect of flling aluminium tubes with different density polyurethane foam was also briefly examined.