c © ESO 2006 Astronomy &Astrophysics

Context. BL Cam is an extreme field multiperiodic short-period low-metallicity high-amplitude SX Phe-type variable where its probably complex pulsational content is subject of controversies. Aims. A comprehensive study has been carried out to investigate the nature and pulsational properties of this object. Methods. The analysis is based on new photometric data collected during the last few years at different sites, as well as on all available previously published data. Frequency analyses have been performed on a number of reliable data sets to analyse the pulsational content. In addition, the classical O−C method was used to study the behaviour of the main period. Results. Our frequency analysis confirms some aspects on the multiperiodicity of BL Cam, previously found by other authors, showing a number of secondary modes close to the main frequency f0 = 25.5769 cd−1. The secondary modes present eventua