The literature on opium addiction in Asia reveals widely different sex ratios. Analysis of these reports indicates that community surveys provide the most reliable and valid ratios. Surveys in psychiatric hospitals appear to overreport women, while case registers and surveys in addiction treatment facilities, vends and dens overreport men. The relative proportion of female addicts is greatest in poppy-producing areas and in communities with high prevalence rates of addiction. Instrumental mechanisms for these observations are explored.