Introduction. This study examined (a) changes in crystal methamphetamine use among regular ecstasy users (REU) in Australia and (b) associations of crystal use and smoking with demographics, drug use and harm. Design and Methods. Cross-sectional surveys (2000 - 06) of REU in three Australian capital cities, and in 2006, 750 REU in all Australian capital cities. The interview included: demographics, drug use, risk behaviour, recent criminal activity and methamphetamine dependence using Severity of Dependence Scale. Results. There was little change in overall methamphetamine use, but a marked increase in crystal methamphetamine smoking. Among recent methamphetamine users in 2006 (n = 606), crystal methamphetamine users (n = 364) reported more frequent methamphetamine use and higher levels of dependence. Compared with those who had used only other forms of methamphetamine, recent crystal methamphetamine users were more likely to 'binge' on drugs for 48 hours, engage in crime and experience financial and legal problems related to drug use. Non-smoking crystal methamphetamine users (n = 78) more often reported recent injecting and heroin use. Recent smokers were more likely to have: greater polydrug use, recently overdosed on a 'party drug', and accessed medical services for their drug use. Many of these associations were accounted for by their injecting and heavier methamphetamine use, rather than smoking per se. Conclusions. Crystal methamphetamine smoking among REU has increased markedly and is associated with significant harm. This appears related to smokers' heavier levels of methamphetamine use. Effective harm reduction strategies should be tailored to these specific risks.