The objective of this study was to determine the duration between onset of symptoms of early symptomatic syphilis and diagnosis among men who have sex with men (MSM). A review of cases of primary and secondary syphilis among MSM presented to the Melbourne Sexual Health Centre between January 2003 and August 2007. The mean age of the 123 MSM included was 37 years. Fifty-two percent (n = 64) presented with primary syphilis and 48% (n = 59) with secondary syphilis. Twenty-five percent were HIV-positive. The median rapid plasma reagin titre was 1:32. Of the 34 men referred by general practitioners, referring practitioners did not consider the diagnosis of syphilis in 10 cases of primary syphilis and 20 cases of secondary syphilis. For primary and secondary cases combined, the median duration between onset of symptoms and diagnosis, and onset of symptoms and treatment, was 15 (3-56) and 20 (1-57) days, respectively. The respective durations for secondary syphilis (17 and 23 days) was longer than for primary syphilis (13 and 15 days) (P < 0.05). The mean number of sex partners reported for the prior three months was 8.8 (range 1-15). If early detection and treatment of syphilis is to be optimized in order to improve syphilis control, greater awareness of its symptoms and signs of syphilis need to be promoted among both health-care providers and affected communities.