Background: Typically, females have higher rates of suicide attempts than that of males, while the mortality from suicide shows a reverse pattern.The male to female suicide gender ratio is smaller in several Asian countries when compared to the West.Taipei City experienced an increase in male-to-female suicide gender ratio, from 1.927 to 2.234, during the period 2004 to 2006, accompanied with no change in gender ratio of overall attempted suicide rates.We examined the impact of the change in age-, gender-and method-specific incidence of suicide attempts and case fatality on this increasing suicide rate gender ratio.Aim: This study aimed to quantify the contributions of two main factors, age-, gender-and method-specific incidence of attempted suicide and case fatality, to the widening gap of male to female suicide rate ratio.Methods: The "direct versus compositional decomposition" was performed to examine the relative change of male to female suicide rate ratio for the two periods 2004-2005 and 2005-2006.Completed suicide data were obtained from the Death Certification System of Department of Health in Taiwan issued in 2004, 2005 and 2006 while data of suicide attempts were obtained from the suicide attempt surveillance system run by the Taipei City Suicide Research and Prevention Centre.Results: The relative increases in the male to female suicide rate ratio were estimated to be 0.094 and 0.054 for 2004-2005 and 2005-2006 respectively.Using a "direct versus compositional decomposition" analysis, we show that: (1) the main contributor to the widening gender gap in both periods was the difference in incidence of suicide attempts between genders (0.063 in the first study period and 0.123 in the second).It was estimated that 115.4% and 56.7% of the relative increase in suicide gender ratio were attributed by the relatively higher increase in number of attempts for male using charcoal burning and hanging during 2004-2005; (2) In both study periods, attempters from the age-group 40-59 contributed primarily (over 100%) to the relative increase.Conclusion: The increase in suicide gender ratio from 2004 to 2006 in Taipei City was mainly due to a relative larger inflow of working-age males into the pool of suicide attempts than that of females, with males having higher intention to choose more lethal methods for their suicidal acts, such as charcoal burning, hanging and jumping.