The presence of cyclodextrins in perfusion fluid can enhance microdialysis relative recovery, although at the present time there is no way to predict this based on thermodynamics. In this work, the presence of cyclodextrins in a solution on the relative recovery of phosphotyrosine was explored. Samples of phosphotyrosine were collected via microdialysis sampling techniques using HPLC-grade water as the control and a 0.5% solution of beta-cylodextrin (B-CD) as the experimental perfusion fluid. Samples were collected at three different flow rates, 0.5 �l/min, 1.0 �l/min, and 1.5 �l/min, and an HPLC method for phosphotyrosine using a Hyperclone 3�, C18 column and HPLC-grade water as the mobile phase was developed to analyze the samples. It was found that the presence of beta-cyclodextrin in the perfusion fluid enhanced the relative recovery of phosphotyrosine as much as 2.38 times at the lower flow rate of 0.5 �l/min. At the higher flow rates of 1.0 �l/min and 1.5 �l/min the average enhancement was closer to 1.75 and 1.4 times, respectively. Investigation into the kinetics of the reaction between B-CD and phosphotyrosine is ongoing to determine if microdialysis relative recovery can be predicted for all molecules.