Purpose. With the use of steroid premedication, the incidence of severe hypersensitivity reactions (S- HSR) to paclitaxel is estimated to be 2% . For those who develop a S- HSR to paclitaxel, docetaxel has been employed as an alternative agent though the presence of cross-sensitivity has not been established. We sought to define the incidence of S- HSR to docetaxel following a paclitaxel S- HSR in an academic women’s cancer program. Methods. Patients treated with either paclitaxel (P) or docetaxel (D) between 11/1999 and 8/2004 were identified through our pharmacy database. Records were reviewed and data collected on those patients who had a S- HSR, defined as symptoms for which drug was discontinued, to P, D, or both. Results. 718 patients received P and 93 received D. 59 received D following treatment with P. The presence of S- HSR for P was 2.2% (16/718 patients) and for D was 9.7% (9/93 patients). 10 patients with S- HSR to P crossed over to D and all nine patients reacting to D had a prior reaction to P for a cross-sensitivity rate of 90% (9/10 patients). Conclusions. Cross sensitivity of D after P was 90% at our institution. Given the different vehicles used in P and D, it is likely attributed to the taxane moiety. Caution is required with re-challenge of patients with docetaxel if they have previously reacted to paclitaxel. Purpose. With the use of steroid premedication, the incidence of severe hypersensitivity reactions (S-HSR) to paclitaxel is estimated to be 2%. For those who develop a S-HSR to paclitaxel, docetaxel has been employed as an alternative agent though presence of cross-sensitivity has not been established. We sought to define the incidence of S-HSR to docetaxel following a paclitaxel S-HSR in an academic women’s cancer program. Methods treated with either paclitaxel (P) or docetaxel (D) Between 11/1999 and 8/2004 were identified through our pharmacy database. Records were reviewed and data collected on those patients who had a S-HSR, defined as symptoms for which drug was discontinued, to P, D, or both. Results. 718 patients received P and 93 received D. 59 received D following treatment with P. The presence of S-HSR for P was 2.2% (16/718 patients) and for D was 9.7% (9/93 patients). 10 patients with S-HSR to P crossed over to D and all nine patients reacting to D ha da prior reaction to P for a cross-sensitivity rate of 90% (9/10 patients). Conclusions. Cross-sensitivity of D after P was 90% at our institution. Given the different vehicles used in P and D, it is likely attributed to the taxane moiety. Caution is required with re-challenge of patients with docetaxel if they have previously reacted to paclitaxel.