SummaryThough often considered as obsolete, the recalcification time is still advocated by some authors in the control of heparin therapy and is utilized by many routine laboratories.As there are very few published comparisons between this test and the APTT, the present study was undertaken in order to compare the in vitro sensitivity to heparin, the stability and the reproducibility of both tests.It is concluded that the recalcification time is clearly inferior to APTT for all parameters measured, and that it should generally be abandoned.