BACKGROUND How foam is created for sclerotherapy varies and is not standardized. Moreover, the effect of several factors on the quality of the foam is not well studied. OBJECTIVE To investigate the effects of different parameters on foam stability and bubble size. METHODS As a measure of foam stability, foam half time (FHT) and bubble size distribution were determined for various parameters (polidocanol (POL) concentration, freshness of the POL, syringe size, liquid-to-air ratio, number of pump cycles, and needle size) in the foam creation process. RESULTS FHT was 115 to 157 seconds for POL 1% and 143 to 192 seconds for POL 3%. The other parameters had a limited effect on FHT. POL foam 1% (t=0 seconds) had a mean bubble size of 71 ± 9 µm that increased when the foam was maintained horizontally in the syringe: 102 ± 12 µm) at 30 seconds and 121 ± 20 µm at 60 seconds. The other parameters had no significant influence on bubble size distribution. CONCLUSIONS Higher concentration of POL and rapid injection optimize foam stability and bubble size distribution, but other important foam characteristics are largely independent of differences in the generation and injection of foam.