To quantify ataxia in a simple way four tests were developed and analysed, based on the neurological examination: a tapping test for the arms (test 1), another one for the legs (test 2), a quantified finger-to-nose test (test 3), and a modified Romberg test (test 4). All tests were performed by 115 volunteers, 13 patients with cerebellar ataxia and 25 patients with sensory ataxia due to neuropathy. The test-retest repeatability was excellent. Tests 1, 2 and 4 were age-dependent, with lower scores above age 65. On test 1, 2 and 4 both groups of patients performed worse than controls; the correlation with the ataxia scale of Nobile-Orazio and the modified disability Rankin scale was good (P < 0.05). Although test 3 could differentiate between sensory and cerebellar ataxia, it was not useful for quantifying the degree of ataxia. To determine the practical value of the four tests, 11 patients performed the tests for a second time after a follow up period of 16 months. The results indicate that tests 1, 2 and 4 are sensitive for the detection of ataxia and of changes in its severity.