BACKGROUND AND PURPOSE To characterize the course of secondary progressive multiple sclerosis (SPMS), with an attempt to assess the predictive value of early clinical variables. MATERIAL AND METHODS Medical records of 100 patients with SPMS (40 men, 60 women, aged 34-73) were analyzed retrospectively. Age at onset of MS, first symptoms, annual exacerbation rate (AER), time to progressive phase (TTP), degree of disability at its beginning (Expanded Disability Status Scale; EDSS SP), and annual progression in disability in relapsing-remitting and progressive phases (APD RR and APD SP) were compared for the gender subgroups, and the relationships between them were analyzed. RESULTS Time to progressive phase range was 2-29 years (mean 11.51) and EDSS SP 2-7.5 (mean 5.55). Time to progressive phase in women was longer and EDSS SP was lower than in men. Age at onset of MS, AER and ADP RR correlated positively with TTP. Optic neuritis was the most common first symptom (49%; motor deficit and cerebellar/brainstem involvement 26% and 21%, respectively). Time to progressive phase in the former subgroup was shorter than in the latter, but no differences in ADP SP were found. Annual progression in disability in relapsing-remitting was higher than APD SP. Degree of disability at its beginning (EDSS SP) correlated negatively with ADP SP. CONCLUSIONS Older age at onset, male gender, frequent relapses and fast increase in disability in the relapsing-remitting phase are risk factors for conversion to SPMS. Increase in disability during the progressive phase is slower than in the relapsing-remitting phase and depends mainly on initial EDSS. Individual variability of the course of MS has to be considered.