摘要： The influence of melasma risk factors on the effectiveness of laser toning treatment in Venezuelan females was investigated. Clinical evaluation was performed (n = 64) including ultrasound and thyroid hormone profile. All patients underwent face exposure with laser toning, eight sessions weekly. VISIA percentiles corresponding to dark brown spots determined before and after treatment were compared by ANOVA. Differences between percentile values before and after treatment for each patient were calculated and expressed as percentages. An improvement of ≥30% was considered as significant. Spearman rank correlations between improvement and clinical parameters were determined. A significant increase (p > .005) of the median of the percentiles in the overall group was observed. However, only 62.5% of the patients exhibited an improvement of ≥30% at the right malar, 73.4% at the frontal and 71.8% at the left malar areas. Hormonal contraception during treatment (right malar: p < .0001 left malar: p = .0035), thyroid disorders (right malar: p < .0001; frontal: p = .011; left malar: p < .0001) and photoaging (right malar: p = .0235; frontal: p = .0237; left malar: p = .0137) were inversely associated to melasma improvement after treatment. Prolonged use of sunscreen improved significantly (right malar: p < .001; frontal: p = .016 and left malar: p = .025) treatment effectiveness.