AbstractThe influence of storage on the ESR, determinated simultaneously by a method using heparin and citrate solution as anti-coagulants and by the classical Westergren method, was investigated.Blood samples of 16 patients with a full range of ESR’s were stored for different times. Statistical analysis of results allow us to conclude that storage of anticoagulated blood for :1. 6 hours at room-temperature does not alter results significantly.2. 24 hours at room-temperature causes significant slowing of ESR’s.3. 24 hours at 4°C does not result in significant changes.These conclusions apply equally to both methods of ESR determination studies. Both methods are moreover not-significantly different in this respect.