Background. Contact allergy to rubber additives is common, particularly in patients with occupational dermatitis. Objectives. To descriptively analyse and compare patch test reactions in patients patch tested both with the baseline series and with an additional 'rubber series' as used in the department. Methods. Patch test data from those members of the European Surveillance System on Contact Allergies (ESSCA) network (www.essca-dc.org) who also contributed data on rubber series patch test results were retrospectively analysed. Results. Among 29 522 patients patch tested, 2870 were eligible, that is, patch tested both with the baseline series and with a special rubber series. Of these, 8.8% had positive reaction(s) to one of the baseline screening rubber allergens (as compared with 4.2% in all patients), most often to carba mix, 12.3% had positive reaction(s) to allergens from an additional rubber series, and 6.4% had positive reaction(s) to both. Conclusions. Additional testing with a dedicated rubber series, containing break-down single ingredients of mixes from the baseline series and additional rubber allergens, is warranted in patients with suspected contact allergy to rubber, to avoid false-negative results.