Technical Abstract: Although haploid induction has been practiced in onions for the last 20 years, several obstacles limit its use in plant breeding programmes. To overcome some of them, we investigated three parameters: efficiency of doubled haploid (DH) lines and their selfed progeny as sources of high responsiveness, alternative protocol for chromosome doubling using somatic regeneration of haploid lines and analysis of male fertility of DH lines. Twenty-one DH lines were selfed and tested for haploid induction in the second generation. DH lines retained their rather high embryogenic potential, although induction frequency was lower in 18 lines and higher in 3 lines than in the original lines. This partial loss or gain of gynogenic ability confirms the polygenic inheritance of this trait. Using a two step induction/regeneration procedure, 8,589 somatic regenerants were obtained from 16,170 flower buds; shoot culture was established in all studied lines. A more laborious procedure using extraction of ovaries in the regeneration stage was found equal to flower bud culture at both stages. Chromosome doubling via somatic regeneration was found to be 83% and 100% efficient when the source material was haploid or mixoploid, respectively. Based on the results achieved in this and the previous studies, an alternative protocol for chromosome doubling of gynogenic regenerants is proposed.