Our objective was to compare clinical features and survival in two groups of ALS patients from countries in opposite hemispheres. The study took place at an ALS referral centre in the Limousin region of France (LIM) and in Uruguay (UY). All consecutive patients diagnosed with ALS between 1 January 2002 and 31 December 2004 were enrolled. Data from a total of 187 ALS patients were analysed: 84 from LIM and 103 from UY. Mean ages at onset and diagnosis were significantly higher in LIM (66 vs. 61 years). UY patients demonstrated more advanced disease at the time of diagnosis. The proportions of definite forms were 82% in UY versus 10% in LIM (p<0.001), and median manual muscle testing (MMT) and ALSFRS scores were significantly lower in LIM. This observed difference was not directly explained by a longer diagnostic delay in UY (10 vs. 9 months). Median survival from time of diagnosis was significantly shorter in UY patients (19 vs. 28 months; log-rank test, p=0.030). In conclusion, survival of ALS patients in UY is nine months shorter than in LIM, probably due to the heterogeneity of medical care and the absence of an ALS referral centre.